Systems and methods for efficiently communicating between low-power devices

ABSTRACT

A system includes a first electronic device that activates a first receiver according to a communication schedule that includes a plurality of frames. Each frame is organized according to a grid including a plurality of cells, wherein the cells are associated with a plurality of communication channels and a plurality of time slots. The system also includes a second electronic device that communicates with the first electronic device by transmitting a wake-up packet during a first time slot on a first communication channel. The first time slot and the first communication channel are located at a known position of a respective grid in each frame of the communication schedule. The first electronic device performs an operation based on the wake-up packet after receiving the wake-up packet. The second electronic device also receives a first acknowledgment packet associated with the wake-up packet.

BACKGROUND

The present disclosure relates generally to communication schemesbetween devices in a communication network. More specifically, thepresent disclosure relates generally to enabling devices to communicatewith each other while using power efficiently.

Numerous electronic devices are now capable of connecting to wirelessnetworks. In some instances, the electronic devices communicate betweeneach other using a mesh network. As such, one electronic device may senddata to another electronic device by relaying the data via intermediateelectronic devices. Although relaying data between electronic devices isa useful way to communicate between devices, power may not be usedefficiently by the electronic devices when transmitting and receivingdata between each other.

This section is intended to introduce the reader to various aspects ofart that may be related to various aspects of the present techniques,which are described and/or claimed below. This discussion is believed tobe helpful in providing the reader with background information tofacilitate a better understanding of the various aspects of the presentdisclosure. Accordingly, it should be understood that these statementsare to be read in this light, and not as admissions of prior art.

SUMMARY

A summary of certain embodiments disclosed herein is set forth below. Itshould be understood that these aspects are presented merely to providethe reader with a brief summary of these certain embodiments and thatthese aspects are not intended to limit the scope of this disclosure.Indeed, this disclosure may encompass a variety of aspects that may notbe set forth below.

In one embodiment, a system includes a first electronic device thatactivates a first receiver according to a communication schedule thatincludes a plurality of frames. Each frame is organized according to agrid including a plurality of cells, wherein the cells are associatedwith a plurality of communication channels and a plurality of timeslots. The system also includes a second electronic device thatcommunicates with the first electronic device by transmitting a wake-uppacket during a first time slot on a first communication channel. Thefirst time slot and the first communication channel are located at theknown position of a respective grid in each frame of the communicationschedule. The first electronic device performs an operation based on thewake-up packet after receiving the wake-up packet. The second electronicdevice also receives a first acknowledgment packet associated with thewake-up packet.

In another embodiment, an electronic device that communicates with aplurality of electronic devices disposed in a building includes aprocessor that receives an indication of data to be transmitted to oneof the plurality of electronic devices and identifies a first cell infirst frame of a grid of a communication schedule including a pluralityof frames of the grid. The first cell is associated with a first timeslot and a first communication channel in which the electronic deviceand the one of the plurality of electronic devices are scheduled tocommunicate with each other. The processor also transmits a plurality ofwake-up packets centered at a time within the first time slot to the oneof plurality of electronic devices, such that each of the plurality ofwake-up packets is configured to cause the one of the plurality ofelectronic devices to perform an operation based on a respective wake-uppacket.

In yet another embodiment, a method may include receiving, via aprocessor, a communication schedule comprising a plurality of frames ofa grid, such that the grid is organized with respect to a plurality oftime slots and a plurality of communication channels. Each frameincludes a first cell associated with one of the plurality of timeslots, one of the plurality of communication channels, and two devicesconfigured to communicate with each other. The method may also includeactivating, via the processor, a receiver according to a double sniffinterval, wherein the receiver is configured to receive data packetsfrom one of the two devices, and wherein the receiver is activatedduring the one of the plurality of time slots and on the one of theplurality of communication channels. The method may also includedetecting, via the processor, energy of a wake-up packet when thereceiver is activated and activating, via the processor, the receiverfor a duration of time when the energy is detected. The duration of timecorresponds to an amount of time to receive the wake-up packet. Thewake-up packet comprises instructions to perform an operation configuredto adjust a condition in a building.

Various refinements of the features noted above may exist in relation tovarious aspects of the present disclosure. Further features may also beincorporated in these various aspects as well. These refinements andadditional features may exist individually or in any combination. Forinstance, various features discussed below in relation to one or more ofthe illustrated embodiments may be incorporated into any of theabove-described aspects of the present disclosure alone or in anycombination. The brief summary presented above is intended only tofamiliarize the reader with certain aspects and contexts of embodimentsof the present disclosure without limitation to the claimed subjectmatter.

BRIEF DESCRIPTION OF THE DRAWINGS

Various aspects of this disclosure may be better understood upon readingthe following detailed description and upon reference to the drawings inwhich:

FIG. 1 illustrates a block diagram of a general device that may controland/or monitor a building environment, in accordance with an embodiment;

FIG. 2 illustrates a block diagram of a smart-home environment in whichthe general device of FIG. 1 may communicate with other devices via anetwork layer protocol, in accordance with an embodiment;

FIG. 3 illustrates a network-level view of an extensible devices andservices platform with which the smart-home environment of FIG. 2 can beintegrated, in accordance with an embodiment;

FIG. 4 illustrates an abstracted functional view of the extensibledevices and services platform of FIG. 3, with reference to a processingengine as well as devices of the smart-home environment, in accordancewith an embodiment;

FIG. 5 illustrates a block diagram of an example network of electronicdevices capable of communicating with each other, in accordance with anembodiment;

FIG. 6 illustrates a block diagram of an example network of electronicdevices capable of communicating with each other in the smart-homeenvironment of FIG. 2, in accordance with an embodiment;

FIG. 7 illustrates an example timing diagram that corresponds to howdata may be transmitted between the example electronic devices of FIG.6, in accordance with an embodiment;

FIG. 8 illustrates a grid of communication channels and correspondingtime slots that indicate how data may be transmitted between the exampleelectronic devices of FIG. 6, in accordance with an embodiment;

FIG. 9 illustrates multiple example grids of time slots of FIG. 8, suchthat each grid includes a wake-up time slot, in accordance with anembodiment;

FIG. 10 illustrates an example timing diagram indicating how anelectronic device may be awaken by another electronic device during thewake-up time slot FIG. 9 using a single wake-up packet, in accordancewith an embodiment;

FIG. 11 illustrates a flow chart of a method for transmitting data toanother electronic device within the smart-home environment of FIG. 2,in accordance with an embodiment;

FIG. 12 illustrates a flow chart of a method for receiving data from anelectronic device within the smart-home environment of FIG. 2, inaccordance with an embodiment;

FIG. 13 illustrates a flow chart of a method for determining whether tosend a short chain of wake-up packets to another electronic devicewithin the smart-home environment of FIG. 2, in accordance with anembodiment;

FIG. 14 illustrates a flow chart of a method for determining alikelihood of electronic devices in the smart-home environment of FIG. 2are synchronized with each other, in accordance with an embodiment;

FIG. 15 illustrates a flow chart of a method for adjusting a number ofwake-up packets sent in a chain of wake-up packets as described in theflow chart of FIG. 13, in accordance with an embodiment;

FIG. 16 illustrates an example timing diagram indicating how anelectronic device may be awaken by another electronic device during thewake-up time slot FIG. 9 using the short chain of wake-up packets, inaccordance with an embodiment;

FIG. 17 illustrates an example timing diagram indicating how anelectronic device may be awaken by another electronic device during adouble sniff receiver interval in the wake-up time slot FIG. 9, inaccordance with an embodiment; and

FIG. 18 illustrates a flow chart of a method for detecting atransmission of a wake-up packet using a double sniff receiver intervaland receiving the wake-up packet after detecting the transmission fromanother electronic device within the smart-home environment of FIG. 2,in accordance with an embodiment.

DETAILED DESCRIPTION

One or more specific embodiments of the present disclosure will bedescribed below. These described embodiments are only examples of thepresently disclosed techniques. Additionally, in an effort to provide aconcise description of these embodiments, all features of an actualimplementation may not be described in the specification. It should beappreciated that in the development of any such actual implementation,as in any engineering or design project, numerousimplementation-specific decisions must be made to achieve thedevelopers' specific goals, such as compliance with system-related andbusiness-related constraints, which may vary from one implementation toanother. Moreover, it should be appreciated that such a developmenteffort might be complex and time consuming, but may nevertheless be aroutine undertaking of design, fabrication, and manufacture for those ofordinary skill having the benefit of this disclosure.

When introducing elements of various embodiments of the presentdisclosure, the articles “a,” “an,” and “the” are intended to mean thatthere are one or more of the elements. The terms “comprising,”“including,” and “having” are intended to be inclusive and mean thatthere may be additional elements other than the listed elements.Additionally, it should be understood that references to “oneembodiment” or “an embodiment” of the present disclosure are notintended to be interpreted as excluding the existence of additionalembodiments that also incorporate the recited features.

Embodiments disclosed herein are related to enabling electronic devicesto communicate between each other while using power efficiently. Morespecifically, some of the embodiments disclosed herein are related tousing a fixed time slot in a communication schedule to denote a timeperiod during which a pair of electronic devices may communicate witheach other. In addition to a particular time period, the communicationschedule may provide a communication channel on which the pair ofelectronic devices may communicate with each other. In other words, thecommunication schedule may denote which channel(s) a pair of electronicdevices in a communication network may use to communicate directly witheach other and corresponding time slot(s) in which the communication maytake place.

In one embodiment, the communication schedule may be organized accordingto a number of time slots and a number of communication channels. Thatis, each grid may include a number of cells, such that each cell isassociated with one time slot and one communication channel. Each gridof the communication schedule may include the same number of time slotsthat span the same duration of time; however, the time slots andchannels in which various pairs of electronic devices are designated tocommunicate with each other may change in each grid to ensure that eachpair of electronic devices may have an opportunity to communicate witheach other using different communication channels. By changing thecommunication channels used to communicate data with each other, thepair of electronic devices may not be limited to communicating on a weakcommunication channel relative to other available communicationchannels.

In certain embodiments, the communication schedule may designate atleast one fixed cell in each grid of the communication schedule as awake-up time slot for each pair of electronic devices that are capableof communicating with each other. As such, the fixed cell may indicate atime slot in which one electronic device may receive data from anotherelectronic device and a particular communication channel in which thecommunication may take place. Accordingly, during the wake-up time slot,a receiving electronic device may activate its communication system(e.g., receiver), such that it may receive any wake-up packets beingtransmitted to it on a particular communication channel. In the samemanner, during the same wake-up time slot, a transmitting electronicdevice may transmit a wake-up packet to the receiving electronic deviceon the specified communication channel. After receiving the wake-uppacket, the receiving electronic device may activate its communicationsystem to receive data from the transmitting electronic device accordingto the communication schedule. That is, certain cells in each grid ofthe communication schedule may be associated with the receivingelectronic device and the transmitting electronic device pair. As such,the receiving electronic device and the transmitting electronic devicepair may communicate with each other at different time slots and ondifferent communication channels, thereby minimizing the probability ofcommunicating on a weak communication channel.

By transmitting wake-up packets at a fixed time slot on a particularcommunication channel, the transmitting electronic device maycommunicate data to the receiving electronic device without continuouslyblasting wake-up packets on one or more communication channels until thereceiving electronic device activates its communication system. As aresult, the transmitting electronic device may regularly send data tothe receiving electronic device in a power efficient manner. Moreover,the wake slot also allows for fewer re-sync packets to be sent. Forexample, if a re-sync packet is typically sent every 30 seconds tomaintain the time slot, by using the wake slot, re-sync packets areefficiently sent at each wake slot, which may be after minutes pass, asopposed to seconds.

Smart Device in Smart Home Environment

By way of introduction, FIG. 1 illustrates an example of a generaldevice 10 that may that may be disposed within a building environment.In one embodiment, the device 10 may include one or more sensors 12, auser-interface component 14, a power supply 16 (e.g., including a powerconnection and/or battery), a network interface 18, a processor 20, andthe like.

The sensors 12, in certain embodiments, may detect various propertiessuch as acceleration, temperature, humidity, water, supplied power,proximity, external motion, device motion, sound signals, ultrasoundsignals, light signals, fire, smoke, carbon monoxide,global-positioning-satellite (GPS) signals, radio-frequency (RF), otherelectromagnetic signals or fields, or the like. As such, the sensors 12may include temperature sensor(s), humidity sensor(s), hazard-relatedsensor(s) or other environmental sensor(s), accelerometer(s),microphone(s), optical sensors up to and including camera(s) (e.g.,charged coupled-device or video cameras), active or passive radiationsensors, GPS receiver(s) or radiofrequency identification detector(s).While FIG. 1 illustrates an embodiment with a single sensor, manyembodiments may include multiple sensors. In some instances, the device10 may includes one or more primary sensors and one or more secondarysensors. Here, the primary sensor(s) may sense data central to the coreoperation of the device (e.g., sensing a temperature in a thermostat orsensing smoke in a smoke detector), while the secondary sensor(s) maysense other types of data (e.g., motion, light or sound), which can beused for energy-efficiency objectives or smart-operation objectives.

One or more user-interface components 14 in the device 10 may receiveinput from the user and/or present information to the user. The receivedinput may be used to determine a setting. In certain embodiments, theuser-interface components may include a mechanical or virtual componentthat responds to the user's motion. For example, the user canmechanically move a sliding component (e.g., along a vertical orhorizontal track) or rotate a rotatable ring (e.g., along a circulartrack), or the user's motion along a touchpad may be detected. Suchmotions may correspond to a setting adjustment, which can be determinedbased on an absolute position of a user-interface component 14 or basedon a displacement of a user-interface components 14 (e.g., adjusting aset point temperature by 1 degree F. for every 10° rotation of arotatable-ring component). Physically and virtually movableuser-interface components can allow a user to set a setting along aportion of an apparent continuum. Thus, the user may not be confined tochoose between two discrete options (e.g., as would be the case if upand down buttons were used) but can quickly and intuitively define asetting along a range of possible setting values. For example, amagnitude of a movement of a user-interface component may be associatedwith a magnitude of a setting adjustment, such that a user maydramatically alter a setting with a large movement or finely tune asetting with a small movement.

The user-interface components 14 may also include one or more buttons(e.g., up and down buttons), a keypad, a number pad, a switch, amicrophone, and/or a camera (e.g., to detect gestures). In oneembodiment, the user-interface component 14 may include aclick-and-rotate annular ring component that may enable the user tointeract with the component by rotating the ring (e.g., to adjust asetting) and/or by clicking the ring inwards (e.g., to select anadjusted setting or to select an option). In another embodiment, theuser-interface component 14 may include a camera that may detectgestures (e.g., to indicate that a power or alarm state of a device isto be changed). In some instances, the device 10 may have one primaryinput component, which may be used to set a plurality of types ofsettings. The user-interface components 14 may also be configured topresent information to a user via, e.g., a visual display (e.g., athin-film-transistor display or organic light-emitting-diode display)and/or an audio speaker.

The power-supply component 16 may include a power connection and/or alocal battery. For example, the power connection may connect the device10 to a power source such as a line voltage source. In some instances,an AC power source can be used to repeatedly charge a (e.g.,rechargeable) local battery, such that the battery may be used later tosupply power to the device 10 when the AC power source is not available.

The network interface 18 may include a component that enables the device10 to communicate between devices, servers, routers, and the like. Assuch, the network interface 18 may enable the device 10 to communicatewith other devices 10 or communication-capable components via a wired orwireless network. The network interface 18 may include a wireless cardor some other transceiver connection to facilitate this communication.In any case, the network interface 18 may be capable of communicatingwith a cloud-computing system that may receive data from a variety ofdifferent types of devices 10, each of which may communicate using adifferent communication protocol. The network interface 18 may include areceiving component and a transmitting component capable of receivingdata and transmitting data respectively. In certain embodiments, thenetwork interface 18 may activate the receiving component and/or thetransmitting component based on instructions from the processor 20. Thedata being received or transmitted by the network interface 18 maycorrespond to any number of formats such that it may be communicated viaa wired or wireless manner. As will be appreciated, the networkinterface 18 may enable devices to communicate with each other based ona communication schedule, as will be discussed in greater detail below.Before continuing, it should be noted that there may be more than onenetwork interface 18 within the device 10. As such, the device 10 mayemploy a number of these network interfaces 18 to communicate with otherdevices.

The processor 20 may support one or more of a variety of differentdevice functionalities. As such, the processor 20 may include one ormore processors configured and programmed to carry out and/or cause tobe carried out one or more of the functionalities described herein. Inone embodiment, the processor 20 may include general-purpose processorscarrying out computer code stored in local memory (e.g., flash memory,hard drive, random access memory), special-purpose processors orapplication-specific integrated circuits, combinations thereof, and/orusing other types of hardware/firmware/software processing platforms. Incertain embodiments, the processor 20 may execute operations such asoperating the user-interface component 14 and the like, as well asdetecting a hazard or temperature from the sensor 12.

In some instances, devices may interact with each other such that eventsdetected by a first device influences actions of a second device. Forexample, a first device can detect that a user has entered into a garage(e.g., by detecting motion in the garage, detecting a change in light inthe garage or detecting opening of the garage door). The first devicecan transmit this information to a second device via the networkinterface 18, such that the second device can, e.g., adjust a hometemperature setting, a light setting, a music setting, and/or asecurity-alarm setting. As another example, a first device can detect auser approaching a front door (e.g., by detecting motion or sudden lightpattern changes). The first device may, e.g., cause a general audio orvisual signal to be presented (e.g., such as sounding of a doorbell) orcause a location-specific audio or visual signal to be presented (e.g.,to announce the visitor's presence within a room that a user isoccupying).

Keeping the foregoing in mind, FIG. 2 illustrates an example of asmart-home environment 30 within which one or more of the devices 10 ofFIG. 1, methods, systems, services, and/or computer program productsdescribed further herein can be applicable. The depicted smart-homeenvironment 30 includes a structure 32, which can include, e.g., ahouse, office building, garage, or mobile home. It will be appreciatedthat devices can also be integrated into a smart-home environment 30that does not include an entire structure 32, such as an apartment,condominium, or office space. Further, the smart home environment cancontrol and/or be coupled to devices outside of the actual structure 32including multiple small structures (e.g., detached garage). Indeed,several devices in the smart home environment need not physically bewithin the structure 32 at all. For example, a device controlling a poolheater or irrigation system can be located outside of the structure 32.

The depicted structure 32 includes a plurality of rooms 38, separated atleast partly from each other via walls 40. The walls 40 can includeinterior walls or exterior walls. Each room can further include a floor42 and a ceiling 44. Devices can be mounted on, integrated with and/orsupported by a wall 40, floor 42, ceiling 44, window, door, furniture(e.g., desk), and the like.

In some embodiments, the smart-home environment 30 of FIG. 2 includes aplurality of devices 10, including intelligent, multi-sensing,network-connected devices, that can integrate seamlessly with each otherand/or with a central server or a cloud-computing system to provide anyof a variety of useful smart-home objectives. The smart-home environment30 may include one or more intelligent, multi-sensing, network-connectedthermostats 46 (hereinafter referred to as “smart thermostats 46”), oneor more intelligent, network-connected, multi-sensing hazard detectionunits 50 (hereinafter referred to as “smart hazard detectors 50”), andone or more intelligent, multi-sensing, network-connected entrywayinterface devices 52 (hereinafter referred to as “smart doorbells 52”).According to embodiments, the smart thermostat 46 may include a Nest®Learning Thermostat—1st Generation T100577 or Nest® LearningThermostat—2nd Generation T200577 by Nest Labs, Inc., among others. Thesmart thermostat 46 detects ambient climate characteristics (e.g.,temperature and/or humidity) and controls a HVAC system 48 accordingly.

The smart hazard detector 50 may detect the presence of a hazardoussubstance or a substance indicative of a hazardous substance (e.g.,smoke, fire, or carbon monoxide). The smart hazard detector 50 mayinclude a Nest® Protect that may include sensors 12 such as smokesensors, carbon monoxide sensors, and the like. As such, the hazarddetector 50 may determine when smoke, fire, or carbon monoxide may bepresent within the building.

The smart doorbell 52 may detect a person's approach to or departurefrom a location (e.g., an outer door), control doorbell functionality,announce a person's approach or departure via audio or visual means, orcontrol settings on a security system (e.g., to activate or deactivatethe security system when occupants go and come). The smart doorbell 52may interact with other devices 10 based on whether someone hasapproached or entered the smart-home environment 30.

In some embodiments, the smart-home environment 30 further includes oneor more intelligent, multi-sensing, network-connected wall switches 54(hereinafter referred to as “smart wall switches 54”), along with one ormore intelligent, multi-sensing, network-connected wall plug interfaces56 (hereinafter referred to as “smart wall plugs 56”). The smart wallswitches 54 may detect ambient lighting conditions, detectroom-occupancy states, and control a power and/or dim state of one ormore lights. In some instances, smart wall switches 54 may also controla power state or speed of a fan, such as a ceiling fan. The smart wallplugs 56 may detect occupancy of a room or enclosure and control supplyof power to one or more wall plugs (e.g., such that power is notsupplied to the plug if nobody is at home).

Still further, in some embodiments, the device 10 within the smart-homeenvironment 30 may further includes a plurality of intelligent,multi-sensing, network-connected appliances 58 (hereinafter referred toas “smart appliances 58”), such as refrigerators, stoves and/or ovens,televisions, washers, dryers, lights, stereos, intercom systems,garage-door openers, floor fans, ceiling fans, wall air conditioners,pool heaters, irrigation systems, security systems, and so forth.According to embodiments, the network-connected appliances 58 are madecompatible with the smart-home environment by cooperating with therespective manufacturers of the appliances. For example, the appliancescan be space heaters, window AC units, motorized duct vents, etc. Whenplugged in, an appliance can announce itself to the smart-home network,such as by indicating what type of appliance it is, and it canautomatically integrate with the controls of the smart-home. Suchcommunication by the appliance to the smart home can be facilitated byany wired or wireless communication protocols known by those havingordinary skill in the art. The smart home also can include a variety ofnon-communicating legacy appliances 68, such as old conventionalwasher/dryers, refrigerators, and the like which can be controlled,albeit coarsely (ON/OFF), by virtue of the smart wall plugs 56. Thesmart-home environment 30 can further include a variety of partiallycommunicating legacy appliances 70, such as infrared (“IR”) controlledwall air conditioners or other IR-controlled devices, which can becontrolled by IR signals provided by the smart hazard detectors 50 orthe smart wall switches 54.

According to embodiments, the smart thermostats 46, the smart hazarddetectors 50, the smart doorbells 52, the smart wall switches 54, thesmart wall plugs 56, and other devices of the smart-home environment 30are modular and can be incorporated into older and new houses. Forexample, the devices 10 may be designed around a modular platformconsisting of two basic components: a head unit and a back plate, whichis also referred to as a docking station. Multiple configurations of thedocking station are provided so as to be compatible with any home, suchas older and newer homes. However, all of the docking stations include astandard head-connection arrangement, such that any head unit can beremovably attached to any docking station. Thus, in some embodiments,the docking stations are interfaces that serve as physical connectionsto the structure and the voltage wiring of the homes, and theinterchangeable head units contain all of the sensors 12, processors 28,user interfaces 14, the power supply 16, the network interface 18, andother functional components of the devices described above.

Many different commercial and functional possibilities for provisioning,maintenance, and upgrade are possible. For example, after years of usingany particular head unit, a user will be able to buy a new version ofthe head unit and simply plug it into the old docking station. There arealso many different versions for the head units, such as low-costversions with few features, and then a progression of increasinglycapable versions, up to and including extremely fancy head units with alarge number of features. Thus, it should be appreciated that thevarious versions of the head units can all be interchangeable, with anyof them working when placed into any docking station. This canadvantageously encourage sharing and re-deployment of old head units—forexample, when an important high-capability head unit, such as a hazarddetector, is replaced by a new version of the head unit, then the oldhead unit can be re-deployed to a back room or basement, etc. Accordingto embodiments, when first plugged into a docking station, the head unitcan ask the user (by 2D LCD display, 2D/3D holographic projection, voiceinteraction, etc.) a few simple questions such as, “Where am I” and theuser can indicate “living room”, “kitchen” and so forth.

The smart-home environment 30 may also include communication withdevices outside of the physical home but within a proximate geographicalrange of the home. For example, the smart-home environment 30 mayinclude a pool heater monitor 34 that communicates a current pooltemperature to other devices within the smart-home environment 30 orreceives commands for controlling the pool temperature. Similarly, thesmart-home environment 30 may include an irrigation monitor 36 thatcommunicates information regarding irrigation systems within thesmart-home environment 30 and/or receives control information forcontrolling such irrigation systems. According to embodiments, analgorithm is provided for considering the geographic location of thesmart-home environment 30, such as based on the zip code or geographiccoordinates of the home. The geographic information is then used toobtain data helpful for determining optimal times for watering, suchdata may include sun location information, temperature, dew point, soiltype of the land on which the home is located, etc.

By virtue of network connectivity, one or more of the smart-home devicesof FIG. 2 can further allow a user to interact with the device even ifthe user is not proximate to the device. For example, a user cancommunicate with a device using a computer (e.g., a desktop computer,laptop computer, or tablet) or other portable electronic device (e.g., asmartphone) 66. A web page or app can be configured to receivecommunications from the user and control the device based on thecommunications and/or to present information about the device'soperation to the user. For example, the user can view a current setpoint temperature for a device and adjust it using a computer. The usercan be in the structure during this remote communication or outside thestructure.

As discussed, users can control the smart thermostat and other smartdevices in the smart-home environment 30 using a network-connectedcomputer or portable electronic device 66. In some examples, some or allof the occupants (e.g., individuals who live in the home) can registertheir device 66 with the smart-home environment 30. Such registrationcan be made at a central server to authenticate the occupant and/or thedevice as being associated with the home and to give permission to theoccupant to use the device to control the smart devices in the home. Anoccupant can use their registered device 66 to remotely control thesmart devices of the home, such as when the occupant is at work or onvacation. The occupant may also use their registered device to controlthe smart devices when the occupant is actually located inside the home,such as when the occupant is sitting on a couch inside the home. Itshould be appreciated that instead of or in addition to registeringdevices 66, the smart-home environment 30 makes inferences about whichindividuals live in the home and are therefore occupants and whichdevices 66 are associated with those individuals. As such, thesmart-home environment “learns” who is an occupant and permits thedevices 66 associated with those individuals to control the smartdevices of the home.

In some instances, guests desire to control the smart devices. Forexample, the smart-home environment may receive communication from anunregistered mobile device of an individual inside of the home, wheresaid individual is not recognized as an occupant of the home. Further,for example, a smart-home environment may receive communication from amobile device of an individual who is known to be or who is registeredas a guest.

According to embodiments, a guest-layer of controls can be provided toguests of the smart-home environment 30. The guest-layer of controlsgives guests access to basic controls (e.g., a judicially selectedsubset of features of the smart devices), such as temperatureadjustments, but it locks out other functionalities. The guest layer ofcontrols can be thought of as a “safe sandbox” in which guests havelimited controls, but they do not have access to more advanced controlsthat could fundamentally alter, undermine, damage, or otherwise impairthe occupant-desired operation of the smart devices. For example, theguest layer of controls will not permit the guest to adjust theheat-pump lockout temperature.

A use case example of this is when a guest is in a smart home, the guestcould walk up to the thermostat and turn the dial manually, but theguest may not want to walk around the house “hunting” the thermostat,especially at night while the home is dark and others are sleeping.Further, the guest may not want to go through the hassle of downloadingthe necessary application to their device for remotely controlling thethermostat. In fact, the guest may not have the homeowner's logincredentials, etc., and therefore cannot remotely control the thermostatvia such an application. Accordingly, according to embodiments of theinvention, the guest can open a mobile browser on their mobile device,type a keyword, such as “NEST” into the URL field and tap “Go” or“Search”, etc. In response, the device presents the guest with a userinterface, which allows the guest to move the target temperature betweena limited range, such as 65 and 80 degrees Fahrenheit. As discussed, theuser interface provides a guest layer of controls that are limited tobasic functions. The guest cannot change the target humidity, modes, orview energy history.

According to embodiments, to enable guests to access the user interfacethat provides the guest layer of controls, a local webserver is providedthat is accessible in the local area network (LAN). It does not requirea password, because physical presence inside the home is establishedreliably enough by the guest's presence on the LAN. In some embodiments,during installation of the smart device, such as the smart thermostat,the homeowner is asked if they want to enable a Local Web App (LWA) onthe smart device. Business owners will likely say no; homeowners willlikely say yes. When the LWA option is selected, the smart devicebroadcasts to the LAN that the above referenced keyword, such as “NEST”,is now a host alias for its local web server. Thus, no matter whose homea guest goes to, that same keyword (e.g., “NEST”) is always the URL youuse to access the LWA, provided the smart device is purchased from thesame manufacturer. Further, according to embodiments, if there is morethan one smart device on the LAN, the second and subsequent smartdevices do not offer to set up another LWA. Instead, they registerthemselves as target candidates with the master LWA. And in this casethe LWA user would be asked which smart device they want to change thetemperature on before getting the simplified user interface for theparticular smart device they choose.

According to embodiments, a guest layer of controls may also be providedto users by means other than a device 66. For example, the smart device,such as the smart thermostat, may be equipped with walkup-identificationtechnology (e.g., face recognition, RFID, ultrasonic sensors) that“fingerprints” or creates a “signature” for the occupants of the home.The walkup-identification technology can be the same as or similar tothe fingerprinting and signature creating techniques described in othersections of this application. In operation, when a person who does notlive in the home or is otherwise not registered with the smart home orwhose fingerprint or signature is not recognized by the smart home“walks up” to a smart device, the smart device provides the guest withthe guest layer of controls, rather than full controls.

As described below, the smart thermostat 46 and other smart devices“learn” by observing occupant behavior. For example, the smartthermostat learns occupants' preferred temperature set-points formornings and evenings, and it learns when the occupants are asleep orawake, as well as when the occupants are typically away or at home, forexample. According to embodiments, when a guest controls the smartdevices, such as the smart thermostat, the smart devices do not “learn”from the guest. This prevents the guest's adjustments and controls fromaffecting the learned preferences of the occupants.

According to some embodiments, a smart television remote control isprovided. The smart remote control recognizes occupants by thumbprint,visual identification, RFID, etc., and it recognizes a user as a guestor as someone belonging to a particular class having limited control andaccess (e.g., child). Upon recognizing the user as a guest or someonebelonging to a limited class, the smart remote control only permits thatuser to view a subset of channels and to make limited adjustments to thesettings of the television and other devices. For example, a guestcannot adjust the digital video recorder (DVR) settings, and a child islimited to viewing child-appropriate programming.

According to some embodiments, similar controls are provided for otherinstruments, utilities, and devices in the house. For example, sinks,bathtubs, and showers can be controlled by smart spigots that recognizeusers as guests or as children and therefore prevent water fromexceeding a designated temperature that is considered safe.

In some embodiments, in addition to containing processing and sensingcapabilities, each of the devices 34, 36, 46, 50, 52, 54, 56, and 58(collectively referred to as “the smart devices”) is capable of datacommunications and information sharing with any other of the smartdevices, as well as to any central server or cloud-computing system orany other device that is network-connected anywhere in the world. Therequired data communications can be carried out using any of a varietyof custom or standard wireless protocols (Wi-Fi, ZigBee, 6LoWPAN, etc.)and/or any of a variety of custom or standard wired protocols (CAT6Ethernet, HomePlug, etc.).

According to embodiments, all or some of the smart devices can serve aswireless or wired repeaters. For example, a first one of the smartdevices can communicate with a second one of the smart device via awireless router 60. The smart devices can further communicate with eachother via a connection to a network, such as the Internet 62. Throughthe Internet 62, the smart devices can communicate with a central serveror a cloud-computing system 64. The central server or cloud-computingsystem 64 can be associated with a manufacturer, support entity, orservice provider associated with the device. For one embodiment, a usermay be able to contact customer support using a device itself ratherthan needing to use other communication means such as a telephone orInternet-connected computer. Further, software updates can beautomatically sent from the central server or cloud-computing system 64to devices (e.g., when available, when purchased, or at routineintervals). In certain embodiments, the cloud-computing system 64 mayreceive data from each of the devices within the smart-home environment30, such that the data regarding the smart-home environment 60 may bestored remotely, analyzed, shared with certain service providers, andthe like.

According to embodiments, the smart devices combine to create a meshnetwork of spokesman and low-power nodes in the smart-home environment30, where some of the smart devices are “spokesman” nodes and others are“low-powered” nodes. Some of the smart devices in the smart-homeenvironment 30 are battery powered, while others have a regular andreliable power source, such as by connecting to wiring (e.g., to 120Vline voltage wires) behind the walls 40 of the smart-home environment.The smart devices that have a regular and reliable power source arereferred to as “spokesman” nodes. These nodes are equipped with thecapability of using any wireless protocol or manner to facilitatebidirectional communication with any of a variety of other devices inthe smart-home environment 30 as well as with the central server orcloud-computing system 64. On the other hand, the devices that arebattery powered are referred to as “low-power” nodes. These nodes tendto be smaller than spokesman nodes and can only communicate usingwireless protocols that require very little power, such as Zigbee,6LoWPAN, etc. Further, some, but not all, low-power nodes are incapableof bidirectional communication. These low-power nodes send messages, butthey are unable to “listen”. Thus, other devices in the smart-homeenvironment 30, such as the spokesman nodes, cannot send information tothese low-power nodes.

As described, the smart devices serve as low power and spokesman nodesto create a mesh network in the smart-home environment 30. Individuallow-power nodes in the smart-home environment regularly send outmessages regarding what they are sensing, and the other low-powerednodes in the smart-home environment—in addition to sending out their ownmessages—forward the messages, thereby causing the messages to travelfrom node to node (i.e., device to device) throughout the smart-homeenvironment 30. The spokesman nodes in the smart-home environment 30 areable to “drop down” to low-powered communication protocols to receivethese messages, translate the messages to other communication protocols,and send the translated messages to other spokesman nodes and/or thecentral server or cloud-computing system 64. Thus, the low-powered nodesusing low-power communication protocols are able send messages acrossthe entire smart-home environment 30 as well as over the Internet 62 tothe central server or cloud-computing system 64. According toembodiments, the mesh network enables the central server orcloud-computing system 64 to regularly receive data from all of thesmart devices in the home, make inferences based on the data, and sendcommands back to one of the smart devices to accomplish some of thesmart-home objectives described herein.

As described, the spokesman nodes and some of the low-powered nodes arecapable of “listening”. Accordingly, users, other devices, and thecentral server or cloud-computing system 64 can communicate controls tothe low-powered nodes. For example, a user can use the portableelectronic device (e.g., a smartphone) 66 to send commands over theInternet 62 to the central server or cloud-computing system 64, whichthen relays the commands to the spokesman nodes in the smart-homeenvironment 30. The spokesman nodes drop down to a low-power protocol tocommunicate the commands to the low-power nodes throughout thesmart-home environment, as well as to other spokesman nodes that did notreceive the commands directly from the central server or cloud-computingsystem 64.

An example of a low-power node is a smart night-light 65. In addition tohousing a light source, the smart night light 65 houses an occupancysensor, such as an ultrasonic or passive IR sensor, and an ambient lightsensor, such as a photoresistor or a single-pixel sensor that measureslight in the room. In some embodiments, the smart night-light 65 isconfigured to activate the light source when its ambient light sensordetects that the room is dark and when its occupancy sensor detects thatsomeone is in the room. In other embodiments, the smart night-light 65is simply configured to activate the light source when its ambient lightsensor detects that the room is dark. Further, according to embodiments,the smart night light 65 includes a low-power wireless communicationchip (e.g., ZigBee chip) that regularly sends out messages regarding theoccupancy of the room and the amount of light in the room, includinginstantaneous messages coincident with the occupancy sensor detectingthe presence of a person in the room. As mentioned above, these messagesmay be sent wirelessly, using the mesh network, from node to node (i.e.,smart device to smart device) within the smart-home environment 30 aswell as over the Internet 62 to the central server or cloud-computingsystem 64.

Other examples of low-powered nodes include battery-operated versions ofthe smart hazard detectors 50. These smart hazard detectors 50 are oftenlocated in an area without access to constant and reliable power and, asdiscussed in detail below, may include any number and type of sensors,such as smoke/fire/heat sensors, carbon monoxide/dioxide sensors,occupancy/motion sensors, ambient light sensors, temperature sensors,humidity sensors, and the like. Furthermore, smart hazard detectors 50can send messages that correspond to each of the respective sensors tothe other devices and the central server or cloud-computing system 64,such as by using the mesh network as described above.

Examples of spokesman nodes include smart thermostats 46, smartdoorbells 52, smart wall switches 54, and smart wall plugs 56. Thesedevices 46, 52, 54, and 56 are often located near and connected to areliable power source, and therefore can include more power-consumingcomponents, such as one or more communication chips capable ofbidirectional communication in any variety of protocols.

In some embodiments, these low-powered and spokesman nodes (e.g.,devices 46, 50, 52, 54, 56, 58, and 65) can function as “tripwires” foran alarm system in the smart-home environment. For example, in the eventa perpetrator circumvents detection by alarm sensors located at windows,doors, and other entry points of the smart-home environment 30, thealarm could be triggered upon receiving an occupancy, motion, heat,sound, etc. message from one or more of the low-powered and spokesmannodes in the mesh network. For example, upon receiving a message from asmart night light 65 indicating the presence of a person, the centralserver or cloud-computing system 64 or some other device could triggeran alarm, provided the alarm is armed at the time of detection. Thus,the alarm system could be enhanced by various low-powered and spokesmannodes located throughout the smart-home environment 30. In this example,a user could enhance the security of the smart-home environment 30 bybuying and installing extra smart nightlights 65. However, in a scenariowhere the perpetrator uses a radio transceiver to jam the wirelessnetwork, the devices 10 may be incapable of communicating with eachother. Therefore, as discussed in detail below, the present techniquesprovide network communication jamming attack detection and notificationsolutions to such a problem.

In some embodiments, the mesh network can be used to automatically turnon and off lights as a person transitions from room to room. Forexample, the low-powered and spokesman nodes detect the person'smovement through the smart-home environment and communicatecorresponding messages through the mesh network. Using the messages thatindicate which rooms are occupied, the central server or cloud-computingsystem 64 or some other device activates and deactivates the smart wallswitches 54 to automatically provide light as the person moves from roomto room in the smart-home environment 30. Further, users may providepre-configuration information that indicates which smart wall plugs 56provide power to lamps and other light sources, such as the smartnight-light 65. Alternatively, this mapping of light sources to wallplugs 56 can be done automatically (e.g., the smart wall plugs 56 detectwhen a light source is plugged into it, and it sends a correspondingmessage to the central server or cloud-computing system 64). Using thismapping information in combination with messages that indicate whichrooms are occupied, the central server or cloud-computing system 64 orsome other device activates and deactivates the smart wall plugs 56 thatprovide power to lamps and other light sources so as to track theperson's movement and provide light as the person moves from room toroom.

In some embodiments, the mesh network of low-powered and spokesman nodescan be used to provide exit lighting in the event of an emergency. Insome instances, to facilitate this, users provide pre-configurationinformation that indicates exit routes in the smart-home environment 30.For example, for each room in the house, the user provides a map of thebest exit route. It should be appreciated that instead of a userproviding this information, the central server or cloud-computing system64 or some other device could automatically determine the routes usinguploaded maps, diagrams, architectural drawings of the smart-home house,as well as using a map generated based on positional informationobtained from the nodes of the mesh network (e.g., positionalinformation from the devices is used to construct a map of the house).In operation, when an alarm is activated (e.g., when one or more of thesmart hazard detector 50 detects smoke and activates an alarm), thecentral server or cloud-computing system 64 or some other device usesoccupancy information obtained from the low-powered and spokesman nodesto determine which rooms are occupied and then turns on lights (e.g.,nightlights 65, wall switches 54, wall plugs 56 that power lamps, etc.)along the exit routes from the occupied rooms so as to provide emergencyexit lighting.

Further included and illustrated in the smart-home environment 30 ofFIG. 2 are service robots 69 each configured to carry out, in anautonomous manner, any of a variety of household tasks. For someembodiments, the service robots 69 can be respectively configured toperform floor sweeping, floor washing, etc. in a manner similar to thatof known commercially available devices such as the ROOMBA™ and SCOOBA™products sold by iRobot, Inc. of Bedford, Mass. Tasks such as floorsweeping and floor washing can be considered as “away” or “while-away”tasks for purposes of the instant description, as it is generally moredesirable for these tasks to be performed when the occupants are notpresent. For other embodiments, one or more of the service robots 69 areconfigured to perform tasks such as playing music for an occupant,serving as a localized thermostat for an occupant, serving as alocalized air monitor/purifier for an occupant, serving as a localizedbaby monitor, serving as a localized hazard detector for an occupant,and so forth, it being generally more desirable for such tasks to becarried out in the immediate presence of the human occupant. Forpurposes of the instant description, such tasks can be considered as“human-facing” or “human-centric” tasks.

When serving as a localized thermostat for an occupant, a particular oneof the service robots 69 can be considered to be facilitating what canbe called a “personal comfort-area network” for the occupant, with theobjective being to keep the occupant's immediate space at a comfortabletemperature wherever that occupant may be located in the home. This canbe contrasted with conventional wall-mounted room thermostats, whichhave the more attenuated objective of keeping a statically-definedstructural space at a comfortable temperature. According to oneembodiment, the localized-thermostat service robot 69 is configured tomove itself into the immediate presence (e.g., within five feet) of aparticular occupant who has settled into a particular location in thehome (e.g. in the dining room to eat their breakfast and read the news).The localized-thermostat service robot 69 includes a temperature sensor,a processor, and wireless communication components configured such thatcontrol communications with the HVAC system, either directly or througha wall-mounted wirelessly communicating thermostat coupled to the HVACsystem, are maintained and such that the temperature in the immediatevicinity of the occupant is maintained at their desired level. If theoccupant then moves and settles into another location (e.g. to theliving room couch to watch television), the localized-thermostat servicerobot 69 proceeds to move and park itself next to the couch and keepthat particular immediate space at a comfortable temperature.

Technologies by which the localized-thermostat service robot 69 (and/orthe larger smart-home system of FIG. 2) can identify and locate theoccupant whose personal-area space is to be kept at a comfortabletemperature can include, but are not limited to, RFID sensing (e.g.,person having an RFID bracelet, RFID necklace, or RFID key fob),synthetic vision techniques (e.g., video cameras and face recognitionprocessors), audio techniques (e.g., voice, sound pattern, vibrationpattern recognition), ultrasound sensing/imaging techniques, andinfrared or near-field communication (NFC) techniques (e.g., personwearing an infrared or NFC-capable smartphone), along with rules-basedinference engines or artificial intelligence techniques that draw usefulconclusions from the sensed information (e.g., if there is only a singleoccupant present in the home, then that is the person whose immediatespace should be kept at a comfortable temperature, and the selection ofthe desired comfortable temperature should correspond to that occupant'sparticular stored profile).

When serving as a localized air monitor/purifier for an occupant, aparticular service robot 69 can be considered to be facilitating whatcan be called a “personal health-area network” for the occupant, withthe objective being to keep the air quality in the occupant's immediatespace at healthy levels. Alternatively or in conjunction therewith,other health-related functions can be provided, such as monitoring thetemperature or heart rate of the occupant (e.g., using finely remotesensors, near-field communication with on-person monitors, etc.). Whenserving as a localized hazard detector for an occupant, a particularservice robot 69 can be considered to be facilitating what can be calleda “personal safety-area network” for the occupant, with the objectivebeing to ensure there is no excessive carbon monoxide, smoke, fire,etc., in the immediate space of the occupant. Methods analogous to thosedescribed above for personal comfort-area networks in terms of occupantidentifying and tracking are likewise applicable for personalhealth-area network and personal safety-area network embodiments.

According to some embodiments, the above-referenced facilitation ofpersonal comfort-area networks, personal health-area networks, personalsafety-area networks, and/or other such human-facing functionalities ofthe service robots 69, are further enhanced by logical integration withother smart sensors in the home according to rules-based inferencingtechniques or artificial intelligence techniques for achieving betterperformance of those human-facing functionalities and/or for achievingthose goals in energy-conserving or other resource-conserving ways.Thus, for one embodiment relating to personal health-area networks, theair monitor/purifier service robot 69 can be configured to detectwhether a household pet is moving toward the currently settled locationof the occupant (e.g., using on-board sensors and/or by datacommunications with other smart-home sensors along with rules-basedinferencing/artificial intelligence techniques), and if so, the airpurifying rate is immediately increased in preparation for the arrivalof more airborne pet dander. For another embodiment relating to personalsafety-area networks, the hazard detector service robot 69 can beadvised by other smart-home sensors that the temperature and humiditylevels are rising in the kitchen, which is nearby to the occupant'scurrent dining room location, and responsive to this advisory the hazarddetector service robot 69 will temporarily raise a hazard detectionthreshold, such as a smoke detection threshold, under an inference thatany small increases in ambient smoke levels will most likely be due tocooking activity and not due to a genuinely hazardous condition.

The above-described “human-facing” and “away” functionalities can beprovided, without limitation, by multiple distinct service robots 69having respective dedicated ones of such functionalities, by a singleservice robot 69 having an integration of two or more different ones ofsuch functionalities, and/or any combinations thereof (including theability for a single service robot 69 to have both “away” and “humanfacing” functionalities) without departing from the scope of the presentteachings. Electrical power can be provided by virtue of rechargeablebatteries or other rechargeable methods, such as an out-of-the-waydocking station to which the service robots 69 will automatically dockand recharge its batteries (if needed) during periods of inactivity.Preferably, each service robot 69 includes wireless communicationcomponents that facilitate data communications with one or more of theother wirelessly communicating smart-home sensors of FIG. 2 and/or withone or more other service robots 69 (e.g., using Wi-Fi, Zigbee, Z-Wave,6LoWPAN, etc.), and one or more of the smart-home devices 10 can be incommunication with a remote server over the Internet. Alternatively orin conjunction therewith, each service robot 69 can be configured tocommunicate directly with a remote server by virtue of cellulartelephone communications, satellite communications, 3G/4G network datacommunications, or other direct communication method.

Provided according to some embodiments are systems and methods relatingto the integration of the service robot(s) 69 with home security sensorsand related functionalities of the smart home system. The embodimentsare particularly applicable and advantageous when applied for thoseservice robots 69 that perform “away” functionalities or that otherwiseare desirable to be active when the home is unoccupied (hereinafter“away-service robots”). Included in the embodiments are methods andsystems for ensuring that home security systems, intrusion detectionsystems, and/or occupancy-sensitive environmental control systems (forexample, occupancy-sensitive automated setback thermostats that enterinto a lower-energy-using condition when the home is unoccupied) are noterroneously triggered by the away-service robots.

Provided according to one embodiment is a home automation and securitysystem (e.g., as shown in FIG. 2) that is remotely monitored by amonitoring service by virtue of automated systems (e.g., cloud-basedservers or other central servers, hereinafter “central server”) that arein data communications with one or more network-connected elements ofthe home automation and security system. The away-service robots areconfigured to be in operative data communication with the centralserver, and are configured such that they remain in a non-away-servicestate (e.g., a dormant state at their docking station) unless permissionis granted from the central server (e.g., by virtue of an“away-service-OK” message from the central server) to commence theiraway-service activities. An away-state determination made by the system,which can be arrived at (i) exclusively by local on-premises smartdevice(s) based on occupancy sensor data, (ii) exclusively by thecentral server based on received occupancy sensor data and/or based onreceived proximity-related information such as GPS coordinates from usersmartphones or automobiles, or (iii) any combination of (i) and (ii) canthen trigger the granting of away-service permission to the away-servicerobots by the central server. During the course of the away-servicerobot activity, during which the away-service robots may continuouslydetect and send their in-home location coordinates to the centralserver, the central server can readily filter signals from the occupancysensing devices to distinguish between the away-service robot activityversus any unexpected intrusion activity, thereby avoiding a falseintrusion alarm condition while also ensuring that the home is secure.Alternatively or in conjunction therewith, the central server mayprovide filtering data (such as an expected occupancy-sensing profiletriggered by the away-service robots) to the occupancy sensing nodes orassociated processing nodes of the smart home, such that the filteringis performed at the local level. Although somewhat less secure, it wouldalso be within the scope of the present teachings for the central serverto temporarily disable the occupancy sensing equipment for the durationof the away-service robot activity.

According to another embodiment, functionality similar to that of thecentral server in the above example can be performed by an on-sitecomputing device such as a dedicated server computer, a “master” homeautomation console or panel, or as an adjunct function of one or more ofthe smart-home devices of FIG. 2. In such an embodiment, there would beno dependency on a remote service provider to provide the“away-service-OK” permission to the away-service robots and thefalse-alarm-avoidance filtering service or filter information for thesensed intrusion detection signals.

According to other embodiments, there are provided methods and systemsfor implementing away-service robot functionality while avoiding falsehome security alarms and false occupancy-sensitive environmentalcontrols without the requirement of a single overall event orchestrator.For purposes of the simplicity in the present disclosure, the homesecurity systems and/or occupancy-sensitive environmental controls thatwould be triggered by the motion, noise, vibrations, or otherdisturbances of the away-service robot activity are referenced simply as“activity sensing systems,” and when so triggered will yield a“disturbance-detected” outcome representative of the false trigger (forexample, an alarm message to a security service, or an “arrival”determination for an automated setback thermostat that causes the hometo be heated or cooled to a more comfortable “occupied” set pointtemperature). According to one embodiment, the away-service robots areconfigured to emit a standard ultrasonic sound throughout the course oftheir away-service activity, the activity sensing systems are configuredto detect that standard ultrasonic sound, and the activity sensingsystems are further configured such that no disturbance-detected outcomewill occur for as long as that standard ultrasonic sound is detected.For other embodiments, the away-service robots are configured to emit astandard notification signal throughout the course of their away-serviceactivity, the activity sensing systems are configured to detect thatstandard notification signal, and the activity sensing systems arefurther configured such that no disturbance-detected outcome will occurfor as long as that standard notification signal is detected, whereinthe standard notification signal comprises one or more of: an opticalnotifying signal; an audible notifying signal; an infrared notifyingsignal; an infrasonic notifying signal; a wirelessly transmitted datanotification signal (e.g., an IP broadcast, multicast, or unicastnotification signal, or a notification message sent in an TCP/IP two-waycommunication session).

According to some embodiments, the notification signals sent by theaway-service robots to the activity sensing systems are authenticatedand encrypted such that the notifications cannot be learned andreplicated by a potential burglar. Any of a variety of knownencryption/authentication schemes can be used to ensure such datasecurity including, but not limited to, methods involving third partydata security services or certificate authorities. For some embodiments,a permission request-response model can be used, wherein any particularaway-service robot requests permission from each activity sensing systemin the home when it is ready to perform its away-service tasks, and doesnot initiate such activity until receiving a “yes” or “permissiongranted” message from each activity sensing system (or from a singleactivity sensing system serving as a “spokesman” for all of the activitysensing systems). One advantage of the described embodiments that do notrequire a central event orchestrator is that there can (optionally) bemore of an arms-length relationship between the supplier(s) of the homesecurity/environmental control equipment, on the one hand, and thesupplier(s) of the away-service robot(s), on the other hand, as it isonly required that there is the described standard one-way notificationprotocol or the described standard two-way request/permission protocolto be agreed upon by the respective suppliers.

According to still other embodiments, the activity sensing systems areconfigured to detect sounds, vibrations, RF emissions, or otherdetectable environmental signals or “signatures” that are intrinsicallyassociated with the away-service activity of each away-service robot,and are further configured such that no disturbance-detected outcomewill occur for as long as that particular detectable signal orenvironmental “signature” is detected. By way of example, a particularkind of vacuum-cleaning away-service robot may emit a specific sound orRF signature. For one embodiment, the away-service environmentalsignatures for each of a plurality of known away-service robots arestored in the memory of the activity sensing systems based onempirically collected data, the environmental signatures being suppliedwith the activity sensing systems and periodically updated by a remoteupdate server. For another embodiment, the activity sensing systems canbe placed into a “training mode” for the particular home in which theyare installed, wherein they “listen” and “learn” the particularenvironmental signatures of the away-service robots for that home duringthat training session, and thereafter will suppress disturbance-detectedoutcomes for intervals in which those environmental signatures areheard.

For still another embodiment, which is particularly useful when theactivity sensing system is associated with occupancy-sensitiveenvironmental control equipment rather than a home security system, theactivity sensing system is configured to automatically learn theenvironmental signatures for the away-service robots by virtue ofautomatically performing correlations over time between detectedenvironmental signatures and detected occupancy activity. By way ofexample, for one embodiment an intelligent automatednonoccupancy-triggered setback thermostat such as the Nest LearningThermostat can be configured to constantly monitor for audible and RFactivity as well as to perform infrared-based occupancy detection. Inparticular view of the fact that the environmental signature of theaway-service robot will remain relatively constant from event to event,and in view of the fact that the away-service events will likely either(a) themselves be triggered by some sort of nonoccupancy condition asmeasured by the away-service robots themselves, or (b) occur at regulartimes of day, there will be patterns in the collected data by which theevents themselves will become apparent and for which the environmentalsignatures can be readily learned. Generally speaking, for thisautomatic-learning embodiment in which the environmental signatures ofthe away-service robots are automatically learned without requiring userinteraction, it is more preferable that a certain number of falsetriggers be tolerable over the course of the learning process.Accordingly, this automatic-learning embodiment is more preferable forapplication in occupancy-sensitive environmental control equipment (suchas an automated setback thermostat) rather than home security systemsfor the reason that a few false occupancy determinations may cause a fewinstances of unnecessary heating or cooling, but will not otherwise haveany serious consequences, whereas false home security alarms may havemore serious consequences.

According to embodiments, technologies including the sensors of thesmart devices located in the mesh network of the smart-home environmentin combination with rules-based inference engines or artificialintelligence provided at the central server or cloud-computing system 64are used to provide a personal “smart alarm clock” for individualoccupants of the home. For example, user-occupants can communicate withthe central server or cloud-computing system 64 via their mobile devices66 to access an interface for the smart alarm clock. There, occupantscan turn on their “smart alarm clock” and input a wake time for the nextday and/or for additional days. In some embodiments, the occupant mayhave the option of setting a specific wake time for each day of theweek, as well as the option of setting some or all of the inputted waketimes to “repeat”. Artificial intelligence will be used to consider theoccupant's response to these alarms when they go off and make inferencesabout the user's preferred sleep patterns over time.

According to embodiments, the smart device in the smart-home environment30 that happens to be closest to the occupant when the occupant fallsasleep will be the device that transmits messages regarding when theoccupant stopped moving, from which the central server orcloud-computing system 64 will make inferences about where and when theoccupant prefers to sleep. This closest smart device will be the devicethat sounds the alarm to wake the occupant. In this manner, the “smartalarm clock” will follow the occupant throughout the house, by trackingthe individual occupants based on their “unique signature”, which isdetermined based on data obtained from sensors located in the smartdevices. For example, the sensors include ultrasonic sensors, passive IRsensors, and the like. The unique signature is based on a combination ofwalking gate, patterns of movement, voice, height, size, etc. It shouldbe appreciated that facial recognition may also be used.

According to an embodiment, the wake times associated with the “smartalarm clock” are used by the smart thermostat 46 to control the HVAC inan efficient manner so as to pre-heat or cool the house to theoccupant's desired “sleeping” and “awake” temperature settings. Thepreferred settings can be learned over time, such as by observing whichtemperature the occupant sets the thermostat to before going to sleepand which temperature the occupant sets the thermostat to upon wakingup.

According to an embodiment, a device is positioned proximate to theoccupant's bed, such as on an adjacent nightstand, and collects data asthe occupant sleeps using noise sensors, motion sensors (e.g.,ultrasonic, IR, and optical), etc. Data may be obtained by the othersmart devices in the room as well. Such data may include the occupant'sbreathing patterns, heart rate, movement, etc. Inferences are made basedon this data in combination with data that indicates when the occupantactually wakes up. For example, if—on a regular basis—the occupant'sheart rate, breathing, and moving all increase by 5% to 10%, twenty tothirty minutes before the occupant wakes up each morning, thenpredictions can be made regarding when the occupant is going to wake.Other devices in the home can use these predictions to provide othersmart-home objectives, such as adjusting the smart thermostat 46 so asto pre-heat or cool the home to the occupant's desired setting beforethe occupant wakes up. Further, these predictions can be used to set the“smart alarm clock” for the occupant, to turn on lights, etc.

According to embodiments, technologies including the sensors of thesmart devices located throughout the smart-home environment incombination with rules-based inference engines or artificialintelligence provided at the central server or cloud-computing system 64are used to detect or monitor the progress of Alzheimer's Disease. Forexample, the unique signatures of the occupants are used to track theindividual occupants' movement throughout the smart-home environment 30.This data can be aggregated and analyzed to identify patterns indicativeof Alzheimer's. Oftentimes, individuals with Alzheimer's havedistinctive patterns of migration in their homes. For example, a personwill walk to the kitchen and stand there for a while, then to the livingroom and stand there for a while, and then back to the kitchen. Thispattern will take about thirty minutes, and then the person will repeatthe pattern. According to embodiments, the remote servers or cloudcomputing architectures 64 analyze the person's migration data collectedby the mesh network of the smart-home environment to identify suchpatterns.

In addition, FIG. 3 illustrates an embodiment of an extensible devicesand services platform 80 that can be concentrated at a single server ordistributed among several different computing (e.g., cloud-computingsystem 64) entities without limitation with respect to the smart-homeenvironment 30. The extensible devices and services platform 80 mayinclude a processing engine 86, which may include engines that receivedata from devices of smart-home environments (e.g., via the Internet ora hubbed network), to index the data, to analyze the data and/or togenerate statistics based on the analysis or as part of the analysis.The analyzed data can be stored as derived home data 88.

Results of the analysis or statistics can thereafter be transmitted backto the device that provided home data used to derive the results, toother devices, to a server providing a web page to a user of the device,or to other non-device entities. For example, use statistics, usestatistics relative to use of other devices, use patterns, and/orstatistics summarizing sensor readings can be generated by theprocessing engine 86 and transmitted. The results or statistics can beprovided via the Internet 62. In this manner, the processing engine 86can be configured and programmed to derive a variety of usefulinformation from the home data 82. A single server can include one ormore engines.

The derived data can be highly beneficial at a variety of differentgranularities for a variety of useful purposes, ranging from explicitprogrammed control of the devices on a per-home, per-neighborhood, orper-region basis (for example, demand-response programs for electricalutilities), to the generation of inferential abstractions that canassist on a per-home basis (for example, an inference can be drawn thatthe homeowner has left for vacation and so security detection equipmentcan be put on heightened sensitivity), to the generation of statisticsand associated inferential abstractions that can be used for governmentor charitable purposes. For example, processing engine 86 can generatestatistics about device usage across a population of devices and sendthe statistics to device users, service providers or other entities(e.g., that have requested or may have provided monetary compensationfor the statistics).

According to some embodiments, the home data 82, the derived home data88, and/or another data can be used to create “automated neighborhoodsafety networks.” For example, in the event the central server orcloud-computing architecture 64 receives data indicating that aparticular home has been broken into, is experiencing a fire, or someother type of emergency event, an alarm is sent to other smart homes inthe “neighborhood.” In some instances, the central server orcloud-computing architecture 64 automatically identifies smart homeswithin a radius of the home experiencing the emergency and sends analarm to the identified homes. In such instances, the other homes in the“neighborhood” do not have to sign up for or register to be a part of asafety network, but instead are notified of an emergency based on theirproximity to the location of the emergency. This creates robust andevolving neighborhood security watch networks, such that if one person'shome is getting broken into, an alarm can be sent to nearby homes, suchas by audio announcements via the smart devices located in those homes.It should be appreciated that this can be an opt-in service and that, inaddition to or instead of the central server or cloud-computingarchitecture 64 selecting which homes to send alerts to, individuals cansubscribe to participate in such networks and individuals can specifywhich homes they want to receive alerts from. This can include, forexample, the homes of family members who live in different cities, suchthat individuals can receive alerts when their loved ones in otherlocations are experiencing an emergency.

According to some embodiments, sound, vibration, and/or motion sensingcomponents of the smart devices are used to detect sound, vibration,and/or motion created by running water. Based on the detected sound,vibration, and/or motion, the central server or cloud-computing system64 makes inferences about water usage in the home and provides relatedservices. For example, the central server or cloud-computing system 64can run programs/algorithms that recognize what water sounds like andwhen it is running in the home. According to one embodiment, to map thevarious water sources of the home, upon detecting running water, thecentral server or cloud-computing system 64 sends a message anoccupant's mobile device asking if water is currently running or ifwater has been recently run in the home and, if so, which room and whichwater-consumption appliance (e.g., sink, shower, toilet, etc.) was thesource of the water. This enables the central server or cloud-computingarchitecture 64 to determine the “signature” or “fingerprint” of eachwater source in the home. This is sometimes referred to herein as “audiofingerprinting water usage.”

In one illustrative example, the central server or cloud-computingarchitecture 64 creates a signature for the toilet in the masterbathroom, and whenever that toilet is flushed, the central server orcloud-computing system 64 will know that the water usage at that time isassociated with that toilet. Thus, the central server or cloud-computingsystem 64 can track the water usage of that toilet as well as eachwater-consumption application in the home. This information can becorrelated to water bills or smart water meters so as to provide userswith a breakdown of their water usage.

According to some embodiments, sound, vibration, and/or motion sensingcomponents of the smart devices are used to detect sound, vibration,and/or motion created by mice and other rodents as well as by termites,cockroaches, and other insects (collectively referred to as “pests”).Based on the detected sound, vibration, and/or motion, the centralserver or cloud-computing system 64 makes inferences aboutpest-detection in the home and provides related services. For example,the central server or cloud-computing architecture 64 can runprograms/algorithms that recognize what certain pests sound like, howthey move, and/or the vibration they create, individually and/orcollectively. According to one embodiment, the central server orcloud-computing system 64 can determine the “signatures” of particulartypes of pests.

For example, in the event the central server or cloud-computing system64 detects sounds that may be associated with pests, it notifies theoccupants of such sounds and suggests hiring a pest control company. Ifit is confirmed that pests are indeed present, the occupants input tothe central server or cloud-computing system 64 confirms that itsdetection was correct, along with details regarding the identifiedpests, such as name, type, description, location, quantity, etc. Thisenables the central server or cloud-computing system 64 to “tune” itselffor better detection and create “signatures” or “fingerprints” forspecific types of pests. For example, the central server orcloud-computing system 64 can use the tuning as well as the signaturesand fingerprints to detect pests in other homes, such as nearby homesthat may be experiencing problems with the same pests. Further, forexample, in the event that two or more homes in a “neighborhood” areexperiencing problems with the same or similar types of pests, thecentral server or cloud-computing system 64 can make inferences thatnearby homes may also have such problems or may be susceptible to havingsuch problems, and it can send warning messages to those homes to helpfacilitate early detection and prevention.

In some embodiments, to encourage innovation and research and toincrease products and services available to users, the devices andservices platform 80 expose a range of application programminginterfaces (APIs) 90 to third parties, such as charities 94,governmental entities 96 (e.g., the Food and Drug Administration or theEnvironmental Protection Agency), academic institutions 98 (e.g.,university researchers), businesses 100 (e.g., providing devicewarranties or service to related equipment, targeting advertisementsbased on home data), utility companies 102, and other third parties. TheAPIs 90 are coupled to and permit third-party systems to communicatewith the central server or the cloud-computing system 64, including theservices 84, the processing engine 86, the home data 82, and the derivedhome data 88. For example, the APIs 90 allow applications executed bythe third parties to initiate specific data processing tasks that areexecuted by the central server or the cloud-computing system 64, as wellas to receive dynamic updates to the home data 82 and the derived homedata 88.

For example, third parties can develop programs and/or applications,such as web or mobile apps that integrate with the central server or thecloud-computing system 64 to provide services and information to users.Such programs and application may be, for example, designed to helpusers reduce energy consumption, to preemptively service faultyequipment, to prepare for high service demands, to track past serviceperformance, etc., or to perform any of a variety of beneficialfunctions or tasks now known or hereinafter developed.

According to some embodiments, third-party applications make inferencesfrom the home data 82 and the derived home data 88, such inferences mayinclude when are occupants home, when are they sleeping, when are theycooking, when are they in the den watching television, and when do theyshower. The answers to these questions may help third-parties benefitconsumers by providing them with interesting information, products andservices as well as with providing them with targeted advertisements.

In one example, a shipping company creates an application that makesinferences regarding when people are at home. The application uses theinferences to schedule deliveries for times when people will most likelybe at home. The application can also build delivery routes around thesescheduled times. This reduces the number of instances where the shippingcompany has to make multiple attempts to deliver packages, and itreduces the number of times consumers have to pick up their packagesfrom the shipping company.

To further illustrate, FIG. 4 describes an abstracted functional view110 of the extensible devices and services platform 80 of FIG. 3, withparticular reference to the processing engine 86 as well as devices,such as those of the smart-home environment 30 of FIG. 2. Even thoughdevices situated in smart-home environments will have an endless varietyof different individual capabilities and limitations, they can all bethought of as sharing common characteristics in that each of them is adata consumer 112 (DC), a data source 114 (DS), a services consumer 116(SC), and a services source 118 (SS). Advantageously, in addition toproviding the essential control information needed for the devices toachieve their local and immediate objectives, the extensible devices andservices platform 80 can also be configured to harness the large amountof data that is flowing out of these devices. In addition to enhancingor optimizing the actual operation of the devices themselves withrespect to their immediate functions, the extensible devices andservices platform 80 can be directed to “repurposing” that data in avariety of automated, extensible, flexible, and/or scalable ways toachieve a variety of useful objectives. These objectives may bepredefined or adaptively identified based on, e.g., usage patterns,device efficiency, and/or user input (e.g., requesting specificfunctionality).

For example, FIG. 4 shows processing engine 86 as including a number ofparadigms 120. Processing engine 86 can include a managed servicesparadigm 120 a that monitors and manages primary or secondary devicefunctions. The device functions can include ensuring proper operation ofa device given user inputs, estimating that (e.g., and responding to aninstance in which) an intruder is or is attempting to be in a dwelling,detecting a failure of equipment coupled to the device (e.g., a lightbulb having burned out), implementing or otherwise responding to energydemand response events, or alerting a user of a current or predictedfuture event or characteristic. Processing engine 86 can further includean advertising/communication paradigm 120 b that estimatescharacteristics (e.g., demographic information), desires and/or productsof interest of a user based on device usage. Services, promotions,products or upgrades can then be offered or automatically provided tothe user. Processing engine 86 can further include a social paradigm 120c that uses information from a social network, provides information to asocial network (for example, based on device usage), and/or processesdata associated with user and/or device interactions with the socialnetwork platform. For example, a user's status as reported to theirtrusted contacts on the social network could be updated to indicate whenthey are home based on light detection, security system inactivation ordevice usage detectors. As another example, a user may be able to sharedevice-usage statistics with other users. In yet another example, a usermay share HVAC settings that result in low power bills and other usersmay download the HVAC settings to their smart thermostat 46 to reducetheir power bills.

The processing engine 86 can include achallenges/rules/compliance/rewards paradigm 120 d that informs a userof challenges, competitions, rules, compliance regulations and/orrewards and/or that uses operation data to determine whether a challengehas been met, a rule or regulation has been complied with and/or areward has been earned. The challenges, rules or regulations can relateto efforts to conserve energy, to live safely (e.g., reducing exposureto toxins or carcinogens), to conserve money and/or equipment life, toimprove health, etc. For example, one challenge may involve participantsturning down their thermostat by one degree for one week. Those thatsuccessfully complete the challenge are rewarded, such as by coupons,virtual currency, status, etc. Regarding compliance, an example involvesa rental-property owner making a rule that no renters are permitted toaccess certain owner's rooms. The devices in the room having occupancysensors could send updates to the owner when the room is accessed.

The processing engine 86 can integrate or otherwise utilize extrinsicinformation 122 from extrinsic sources to improve the functioning of oneor more processing paradigms. Extrinsic information 122 can be used tointerpret data received from a device, to determine a characteristic ofthe environment near the device (e.g., outside a structure that thedevice is enclosed in), to determine services or products available tothe user, to identify a social network or social-network information, todetermine contact information of entities (e.g., public-service entitiessuch as an emergency-response team, the police or a hospital) near thedevice, etc., to identify statistical or environmental conditions,trends or other information associated with a home or neighborhood, andso forth.

An extraordinary range and variety of benefits can be brought about by,and fit within the scope of, the described extensible devices andservices platform 80, ranging from the ordinary to the profound. Thus,in one “ordinary” example, each bedroom of the smart-home environment 30can be provided with a smart wall switch 54, a smart wall plug 56,and/or smart hazard detectors 50, all or some of which include anoccupancy sensor, wherein the occupancy sensor is also capable ofinferring (e.g., by virtue of motion detection, facial recognition,audible sound patterns, etc.) whether the occupant is asleep or awake.If a serious fire event is sensed, the remote security/monitoringservice or fire department is advised of how many occupants there are ineach bedroom, and whether those occupants are still asleep (or immobile)or whether they have properly evacuated the bedroom. While this is, ofcourse, a very advantageous capability accommodated by the describedextensible devices and services platform 80, there can be substantiallymore “profound” examples that can truly illustrate the potential of alarger “intelligence” that can be made available. By way of perhaps amore “profound” example, the same bedroom occupancy data that is beingused for fire safety can also be “repurposed” by the processing engine86 in the context of a social paradigm of neighborhood child developmentand education. Thus, for example, the same bedroom occupancy and motiondata discussed in the “ordinary” example can be collected and madeavailable (properly anonymized) for processing in which the sleeppatterns of schoolchildren in a particular ZIP code can be identifiedand tracked. Localized variations in the sleeping patterns of theschoolchildren may be identified and correlated, for example, todifferent nutrition programs in local schools.

As previously discussed, the described extensible devices and servicesplatform 80 may enable communicating emergency information betweensmart-home environments 30 that are linked and/or to the properauthorities. For example, when a burglar breaks into a smart-homeenvironment 30, a home security system may trip and sound an alarmand/or send emergency notifications to the neighbors, the police, thesecurity company, and the like.

Power Efficient Communication Between Devices

As discussed above, the device 10 may include low-power nodes that maybe battery powered and may communicate using power more efficiently, ascompared to the nodes that have a continuous source of power. In certainembodiments, a number of low-power nodes may communicate with each othervia a mesh network. For example, FIG. 5 illustrates an examplecommunication network 130 that may be employed in the smart-homeenvironment 30.

The communication network 130 may include an access point 132, borderrouters 134, high-power routers 136, low-power routers 138, sleepy endnodes 140, and the like. The access point 132 may include a device thatmay have access to another network such as the Internet. Access point132 may be accessible via a Wi-Fi or the like. Border routers 134 mayinclude devices that communicate using Wi-Fi as well as using low-ratewireless personal area networks (LR-WPANs) (e.g., IEEE 802.15.4-capabledevices). As such, the border routers 134 may communicate with theaccess point 132 and other low-power devices such as the high-powerrouters 136, the low-power routers 138, the sleepy end nodes 140, andthe like.

The high-power routers 136 may communicate using the LR-WPANs and maycontinuously operate as a receiver. That is, the high-power routers 136may keep its receiver active or on such that the high-power routers 136may receive any data sent to them at any time. To enable the high-powerrouters 136 to continuously operate in a receive mode, the high-powerrouters 136 may be coupled to a continuous source of power such as a120-volt alternating current (AC) power source provided within thesmart-home environment. The low-power router 138, on the other hand, mayoperate using a battery and thus may transmit and receive data in apower efficient manner. The low-power routers 138 may thus alsocommunicate using the LR-WPANs; however, the low-power routers 138 maybe a duty-cycled router that wakes at certain intervals of time to sendand receive data. Sleepy end nodes 140 may also communicate using theLR-WPANs but may just wake at specific instances to send data but maynot be capable of receiving data by their own accord. That is, thesleepy end nodes 140 may receive data when their parent router cachesdata until the next time the sleepy end node checks in.

With the foregoing in mind, FIG. 6 illustrates an example communicationnetwork 150 that attributes an access point 132, a border router 134,and a number of low-power routers 138 (e.g., 152, 154, 156, and 158 ofFIG. 6) with example devices that may be part of the smart-homeenvironment 30. In one embodiment, the border router 134 may correspondto the smart thermostat 46 and the low-power routers 138 may correspondto the smart hazard detector 50 described above.

As shown in FIG. 6, the devices of the communication network 150 maycommunicate with each other via bi-lateral communication links 160-172between various pairs of devices. For example, low-power router 156 maycommunicate with low-power router 152 via communication link 160. Eachcommunication link 160-172 may correspond to a communication channel(e.g., frequency band at a particular time interval) in which thecorresponding pair of devices may transmit and receive data between eachother. Although FIG. 6 illustrates a particular arrangement of devicesand communication link between the devices, it should be noted that thatthe communication network 150 of FIG. 6 is provided as an example, andthus is not meant to limit the manner in which the devices may beconnected.

In the example communication network 150, the low-power router 156 maytransmit data to the access point 132 via multiple hops across thecommunication network 150. For example, the low-power router 156 maytransmit data to the access point 132 via communication links 160, 166,and 170. In addition to the low-power router 156, it should be notedthat in-structure mobile devices may also be accessible via the accesspoint 132 as well.

In certain embodiments, to wake a neighboring device, a transmittingdevice may continuously blast transmit a wake-up signal across one ormore communication channels for some amount of time to ensure that theneighboring device receives the wake-up signal. For example, FIG. 7illustrates a timing diagram 180 that depicts how the low-power router156 may blast a wake-up packet or continuously transmit a wake-up packet182 for some duration of time. Generally, the duration of time maycorrespond to a sufficient amount of time in which neighboring devicesmay activate their receivers. In one embodiment, devices operating in alow power listening (LPL) mode may activate its receiver for a briefamount of time during a receiver sniff 184 to determine whether anotherdevice is attempting to transmit data to the respective devices. Eachdevice operating in the LPL mode may perform the receiver sniff 184 atregular intervals (e.g., 4 s). However, each device may perform itsrespective sniff at different times on various communication channels oron a set wake-up channel, but other devices may not be aware of theexact times and/or channels at which each respective sniff may occur. Assuch, the transmitting device may continuously transmit the wake-upsignal across multiple communication channels for a certain amount oftime that corresponds to a known time interval between the receiversniffs 184.

As shown in FIG. 7, after the receiving device detects the wake-upsignal during the receiver sniff 184, the receiving device may keep itsreceiver active to receive a real data packet 186 at the end of thewake-up signal blast. Although operating in the LPL mode as depicted inFIG. 7 may provide for an effective way to transmit data to neighboringdevices, transmitting wake-up signals in a blast fashion may consume asignificant amount of power. This consumption of power may not bedesired for low-power router devices that operate using a battery. Thatis, transmitting wake-up signals in a blast fashion as described abovemay enable the low-power router device to transmit wake-up signalsassociated with relatively rare events, such as fire hazard alarms,while still consuming a relatively small amount of power. However, ifthe transmitting device intends to send other types of data (e.g.,sensor data, temperature data, occupancy data, commands) in a moreregular interval, the battery of the low-power router device may limitthe number of data transmissions that the transmitting device mayperform.

To use battery power efficiently, devices capable of communicating witheach other in the smart home environment 30 may operate in some kind oflow-power mode. Operating in the low-power mode may involve deactivatingor placing certain power-consuming components (e.g., processor, radios,sensors, bus peripherals, power domains, clock domains) within thedevice in a sleep state for a certain period of time and periodicallyawaking certain components to detect whether the device should performcertain operations. With this in mind, in certain embodiments, toachieve additional power efficiencies while operating in a low-powermode, each device in the smart home environment 30 may communicate witheach according to a communication schedule that works according to acommon time source across the smart home environment 30. In oneembodiment, the communication schedule may specify a time interval and acorresponding communication channel (e.g., frequency) in which a pair ofdevices may communicate with each other. For example, FIG. 8 illustratesan example communication schedule 200 for the communication network 150.The communication schedule 200 may include a grid of cells organizedaccording to time slots and communication channels. As shown in thecommunication schedule 200 of FIG. 8, each communication link 160-172may be associated with one or more cells and thus one or more time slotand channel pairs. Each cell that is designated to one of thecommunication links 160-172 may facilitate communication between arespective of the devices in the communication network 150 associatedwith the corresponding communication links. For example, according tothe communication schedule 200, the communication link 164 is active att=100 ms on channel 14. In this manner, the low-power router 154 maycommunicate with low-power router 152 at t=100 ms on channel 14.

With this in mind, it should be noted that the communication schedule200 depicted in FIG. 8 may represent a single frame of the communicationschedule 200. As such, in one embodiment, the frame including the griddepicted in the communication schedule 200 may continuously repeat tocontinuously facilitate communication between devices in thecommunication network 150. However, due to various properties (e.g.,electric fields, communication devices, physical barriers) of anyparticular smart home environment 30, each communication channel of thecommunication schedule 200 may not provide a sufficiently similarquality of communication. That is, while one communication channel mayprovide a certain amount of bandwidth for data transmission, anothercommunication channel may provide a lower amount of bandwidth due tovarious types of noise.

Accordingly, in certain embodiments, instead of continuously repeatingthe grid depicted in the communication schedule 200, the communicationschedule 200 may include a number of frames, such that each frame mayhave a different grid that defines different time slots and channelpairs in which each communication link may be active. In this manner,the communication schedule may enable devices to communicate with eachother in a time-synchronization channel hopping (TSCH) scheme. By usinga TSCH scheme, the communication schedule may randomly orpseudo-randomly assign time slots and communication channel pairs (i.e.,cell) for each communication link 160-182 during each successive frameof the communication schedule 200. As such, the communication network150 may provide a more robust communication network in which the devicesof the network may communicate with each other. For example, if a pairof devices is scheduled to communicate with each other on a relativelyweak communication channel in one frame, the same pair of devices may bescheduled to communicate with each other on a different communicationchannel, which may be a better communication channel, in the next frame.

In certain embodiments, each device of the communication network 150 mayhave access to the communication schedule 200. As such, when one devicedesires to communicate with another device, the transmitting device maysend a wake-up packet on a particular channel at a designated time slotbased on the communication schedule 200. However, although using theTSCH scheme may provide improved data transmission quality betweendevices, the success of communication between each device using the TSCHscheme is largely dependent on each device being in sync with each otherwith respect to time. That is, if a clock in one device drifts andbecomes out of sync with the clock of another device, the transmissionof data between each other may be jeopardized if the transmitting devicesends a wake-up packet at a designated time slot but is not received bythe receiving device due to the drift in synchronization. Generally,devices may use crystal oscillators or the like to operate a clock. Theability of a clock to maintain a precise time and not to drift maydepend on the quality of the respective crystal oscillator.

Keeping the foregoing in mind, in one embodiment, the communicationschedule 200 may include one fixed cell (time slot and channel pair) inthe grid that may serve as a wake-up slot 202 for each frame of thecommunication schedule 200. In other words, although the communicationschedule 200 may operate according to a TSCH scheme, at least one of thetime slot-channel windows may continuously repeat in the same time sloton the same channel for each frame (e.g., frame 200, frame 204, frame206), as illustrated in FIG. 9. In certain embodiments, a wake-up slotmay be defined for each pair of devices that communicate directly witheach other. The known wake-up slot may be predetermined and communicatedto each other when joining the communication network 150. Alternatively,two devices may collectively determine a wake-up slot for each device totransmit wake-up packets. Additionally, a common wake-up slot may bedefined such that a set of devices will listen at regularly, and any ofthe devices sharing that wake slot can transmit the wake-up packet andwake one or more nodes in the set. In any case, during the wake-up slot202, the receiving device may sniff or activate its receiver todetermine whether a wake-up packet is being sent from a transmittingdevice. If a wake-up packet is received, the receiving device mayprepare to receive data during one or more time slots in which the pairof communicating devices may be scheduled to communicate with each otheras per the communication schedule 200. Alternatively, after the wake-uppacket is received, the receiving device may allow for an out-of-bandcommunication outside the regular communication schedule. That is, uponreceipt of a wake-up packet, the receiving device may remain active andcontinue receiving for one or more time slots immediately afterreceiving the wake-up packet.

By employing a fixed cell (e.g., time slot and communication channelpair) of the communication schedule 200 to communicate a wake-up packet,the transmitting device no longer continuously blasts wake-up packetsfor an extended period of time on one or more communication channels.Instead, the transmitting device may transmit a wake-up packet duringthe wake-up time slot 202 on a particular communication channel when itdesires to transmit data to the receiving device. As a result, thetransmitting device may significantly reduce the amount of transmissionsthat it may perform to transfer data to the receiving device.

It should be noted that although the communication schedule 200 isdescribed as using a fixed cell for its wake-up time slot 202, incertain embodiments, the wake-up time slot 202 may also be implementedin non-fixed cells (e.g., random cells). Regardless of how the wake-uptime slot 202 is scheduled, so long as each device is aware of theappropriate time and channel in which the wake-up time slot 202 shouldoccur, the following techniques may be used to ensure that data issuccessfully transmitted throughout the communication network 150 or thelike.

With the foregoing in mind, FIG. 10 illustrates an example timingdiagram 210 associated with the transmission of a wake-up packet and thereception of the wake-up packet during wake-up time slot 202 by thetransmitting device (e.g., low-power router 156) and the receivingdevice (e.g., low-power router 152), respectively, during the wake-upslot 202. For discussion purposes, the example timing diagram 210 willbe discussed with respect to the low-power router 156 transmitting datato the low-power router 152 of the communication network 150. However,it should be noted that the transmission and reception of a wake-uppacket depicted in FIG. 10 may be performed by any type of device in thesmart home environment 30.

Referring now to FIG. 10, the low-power router 156 may transmit awake-up packet 212 to the low-power router 152 during the wake-up slot202 of the communication schedule 200. In one embodiment, the wake-uppacket 212 may be transmitted by the low-power router 156 during areceiver sniff interval 214 (Δt_(sniff)). The receiver sniff interval214 may correspond to a period of time in which the low-power router 152may activate its receiver, such that the low-power router 152 may detectwhether a start of frame of the wake-up packet 212, which may includeany clock drift that may have occurred since a previous timesynchronization signal was received, is being transmitted. If timesynchronization events are occurring often enough to maintain a clockdrift of less than +/−1 ms, then the duration of the receiver sniffinterval 214 may be at least, for example, 2 ms.

With the receiver sniff interval 214 in mind, the low-power router 152may transmit the wake-up packet 212, such that the transmission of thewake-up packet 212 is centered on time T₂ or the middle of the receiversniff interval 214. By centering the transmission of the wake-up packet212 on the middle of the receiver sniff interval 214, the low-powerrouter 156 may enable the low-power router 156 to receive the wake-uppacket 212 even if the clock of the low-power router 156 has driftedwith respect to the clock of the low-power router 152, or vice-versa. Incertain embodiments, the receiver sniff interval 214 occurs after aknown offset of time has passed from the start of the wake-up time slot202. As such, when centering the transmission of the wake-up packet 212on time T₂, the low-power router 152 may use the known offset time todetermine when to transmit the wake-up packet 212. Further, the knownoffset of time may also be used to communicate a time between thelow-power router 152 and other components in the smart home environment30.

In one embodiment, the wake-up packet 212 may include timesynchronization information, such that the clock of the low-power router152 and the clock of the low-power router 156 may be in sync with eachother. In addition to the time synchronization information, the wake-uppacket 212 may include additional information such as a size of datathat may be transmitted to the low-power router 152 from the low-powerrouter 156 or the like.

After receiving the wake-up packet 212, the low-power router 156 maytransmit an acknowledgement packet 216 to the low-power router 152. Assuch, after transmitting the wake-up packet 212, the low-power router152 may activate its receiver to receive the acknowledgement packet 216.In one embodiment, the acknowledgement packet 216 may also include timesynchronization information from the perspective of the low-power router156. That is, the acknowledgement packet 216 may include a time stampfrom a clock of the low-power router 156 that may be used to synchronizewith a clock of the low-power router 152.

After sending and receiving the wake-up packet 212, the low-power router156 and the low-power router 152 may negotiate or determine how they maycommunicate to send and receive subsequent data packets. For example,the low-power router 156 and the low-power router 152 may determinewhether to send data packets immediately following the transmission andreception of the acknowledgement packet 216 or based on the scheduledcommunication times, as per the communication schedule 200.

Keeping the foregoing in mind, FIG. 11 illustrates a flowchart of amethod 220 that the low-power router 156 (i.e., transmitting device) mayemploy when transmitting data to the low-power router 152 (i.e.,receiving device) using a single wake-up packet. Although the method 220is described as being performed by a processor associated with thelow-power router 156, it should be noted that the method 220 may beperformed by any type of device 10 that may be part of the smart homeenvironment 30.

Referring now to FIG. 11, at block 222, a processor of the low-powerrouter 156 may receive an indication of data that is to be transmittedto a neighboring node or device (e.g., low-power router 152). The datamay correspond to any type of data that the processor may be programmedto share or communicate with a neighboring node. In certain embodiments,the data may correspond to an alarm related to a hazardous event (e.g.,carbon monoxide, fire). The data may also correspond to non-alarm eventssuch as sensor reading or requested commands.

For example, the sensor readings may correspond to measurements acquiredby sensors associated with the low-power router 156. The measurementsmay include temperature measurements, occupancy information, and thelike. The commands may correspond to commands to operate another device10 in the smart home environment. For instance, a command may requestthat a front door be unlocked. The data may also include informationidentifying the low-power router 156 as a new node in the communicationnetwork 150, thereby joining the communication network 150.

At block 224, the processor may determine a wake-up time slot in thecommunication schedule 200 associated with the low-power router 152.After identifying the wake-up time slot, the processor may, at block226, transmit the wake-up packet 212 to the low-power router 152. In oneembodiment, the processor may schedule the transmission of the wake-uppacket 212 centered at the receiver sniff interval 214.

At block 228, the processor may determine whether an acknowledgmentpacket associated with the transmitted wake-up packet 212 was receivedfrom the low-power router 152. If the acknowledgment packet was notreceived, the processor may return to block 226 and retransmit thewake-up packet 212 during the wake-up slot 202 in a subsequent frame oftime slots and channels in the communication schedule 200.

If the processor receives the acknowledgment packet, the processor mayproceed to block 230. At block 230, the processor may send one or moredata packets associated with the data received at block 222 to thelow-power router 152. In certain embodiments, the processor maynegotiate or arbitrate with the low-power router 152 when to send theone or more data packets to the low-power router 152. For example, theprocessor may determine to send the data packets to the low-power router152 during one or more time slots and one or more correspondingcommunication channels designated for bilateral communication betweenthe low-power router 152 and the low-power router 156, as specified bythe communication schedule 200. In another example, the wake-up packet212 may specify which time slots of the communication schedule 200 thatthe data packet may be sent at block 230. In yet another example, theprocessor may indicate to the low-power router 156 that the data packetswill be sent immediately after the acknowledgement packet 216 wasreceived.

In addition to sending the data packets associated with the datareceived at block 222 to the low-power router 152, the processor may usetime synchronization information stored in the acknowledgement packet tosync the clock of the of the low-power router 156 with the clock of thelow-power router 152. That is, the time synchronization information mayinclude a time stamp of the acknowledgement packet or a known offsetfrom the start of a wake slot, both of which may be used to sync theclock of the of the low-power router 156 with the clock of the low-powerrouter 152.

After sending the data packet(s), at block 232, the processor of thelow-power router 156 may receive a data packet acknowledgment from thelow-power router 152. The data packet acknowledgment indicates that thelow-power router 152 has properly received (e.g., error-free) the datapacket transmitted by the low-power router 156.

With the method 220 in mind, FIG. 12 illustrates a flowchart of a method240 that a processor of the low-power router 152 (i.e., receivingdevice) may perform when being awaken to receive data from the low-powerrouter 156 (i.e., transmitting device). As mentioned above with regardto the method 220, although the method 240 is described as beingperformed by a processor associated with the low-power router 152, itshould be noted that the method 240 may be performed by any type ofdevice 10 that may be part of the smart home environment 30.

Referring now to FIG. 12, at block 242, the processor of the low-powerrouter 152 may activate a receiver component of the network interface 18to listen for the transmission of wake-up packets. In one embodiment,the processor may activate the receiver of the low-power router 152 fora period of time (e.g., ˜2 ms) during the receiver sniff interval 214.

At block 244, the processor may detect whether the start of the wake-uppacket 212 is being transmitted to the low-power router 152. If theprocessor detects that the start of the wake-up packet 212 is beingtransmitted during receiver sniff interval 214, the processor mayproceed to block 246 and begin to receive the wake-up packet 212. If theprocessor does not detect that the start of the wake-up packet 212 isbeing transmitted during the receiver sniff interval 24, the processormay return to block 242 and activate its receiver during the wake-upslot of a subsequent frame of time slots and communication channels.

After receiving the wake-up packet 212, at block 248, the processor maytransmit an acknowledgment packet 216 indicating that the wake-up packet212 has been received by the low-power router 152. As mentioned above,the acknowledgment packet 216 may include time synchronizationinformation that may be used to sync the clocks of the low-power router156 and the low-power router 152. In certain embodiments, before sendingthe acknowledgment, the processor of the low-power router 152 maydetermine whether the received wake-up packet 212 is error-free.

At block 250, the processor of the low-power router 152 may analyze thewake-up packet 212 and synchronize the clock of the low-power router 152with time information that may be provided by the wake-up packet 212.The time information of the wake-up packet 212 may correspond to a timeof the clock of the low-power router 156. In this manner, the low-powerrouter 152 (i.e., receiving device) and the low-power router 156 (i.e.,transmitting device) may be in sync with each other. As a result, thelow-power router 156 may precisely send the wake-up packet 212 in anyfuture transmission, such that the wake-up packet 212 is centered at thereceiver sniff interval 214.

At block to 252, the processor of the low-power router 152 may prepareto receive a data packet being transmitted by the low-power router 156.In certain embodiments, the processor may identify one or more timeslots and one or more corresponding communication channels in which thelow-power router 152 may receive the data packet based on thecommunication schedule 200. Alternatively, as mentioned above, theprocessor may prepare to receive the data packet based on negotiated orarbitrated time slots as specified by the low-power router 156.

After determining the appropriate time slot(s) and correspondingcommunication channel(s), at block 254, the processor may beginreceiving the data packet(s) at the respective time slot(s) and therespective communication channel(s). After receiving the data packet(s)from the low-power router 156, the processor of the low-power router 152may determine whether the received data packet(s) were properlyreceived. In one embodiment, the processor may verify that the datapacket(s) were received free of errors. After verifying that the datapacket(s) were properly received, the processor may send anacknowledgment related to the reception of each data packet to thelow-power router 156.

Although the techniques described above for sending a single wake-uppacket centered at the receiver sniff interval 214 is useful inefficiently waking neighboring nodes, if the transmitting device and thereceiving device have clocks that are out of sync with each other, thesingle wake-up packet may not be received by the low-power router 152.As such, in some embodiments, the low-power router 152 may send a shortchain of wake-up packets 212 or more than one wake-up packet 212centered at the receiver interval sniff 214.

With the foregoing in mind, FIG. 13 illustrates a flow chart of a method258 for sending a chain of wake-up packets 212. As mentioned above withregard to the methods 220 and 240, although the method 258 is describedas being performed by a processor associated with the low-power router156, it should be noted that the method 258 may be performed by any typeof device 10 that may be part of the smart home environment 30.

Referring now to FIG. 13, at block 259, the processor of the low-powerrouter 156 may receive an indication of data to be transmitted to thelow-power router 152 (e.g., neighbor node), as described above withregard to block 222. At block 260, the processor may determine whetherit is unlikely that the low-power router 152 is out of sync with thelow-power router 156. That is, the processor may determine thelikelihood that the clocks of the low-power router 152 and the low-powerrouter 156 have drifted with respect to each other.

In one embodiment, the likelihood that the clocks of the low-powerrouter 152 and the low-power router 156 have drifted with respect toeach other may be determined by tracking the amount of time since lastcommunication occurred between each other or between the respectivedevice and a neighbor node. That is, the time drift may be a function oftime since last sync. Additionally, an estimated drift rate of theneighbor node may be tracked based on a weighted average of a sync error(ppm) at each sync event. As such, the estimated drift may be theproduct of an amount of time since a last sync with a neighbor node(time_since_last_heard) and the sync error (sync_error). Further, thesender can forward correctly based on the estimated drift and center thewake packet on the expected time the neighbor will be sniffing. Thisallows the wake chain duration to be decreased, thereby providingadditional power savings.

If, at block 260, the processor determines that the low-power router 156is unlikely to be out of sync with the low-power router 152, theprocessor may proceed to block 261 and send a single wake-up packet 212,as described above with regard to FIG. 11. However, if the processordetermines that the low-power router 156 is likely to be out of syncwith the low-power router 152, the processor may proceed to block 262and send a chain of wake-up packets 212. In one embodiment, the minimumlength of the wake up chain may be calculated by estimating a maximumdrift that has occurred.

Referring back to block 260, to determine whether it is unlikely thatthe low-power router 152 and the low-power router 156 are out of synchwith each other, the processor may perform the method 263 illustrated inFIG. 14. As shown in the method 263, at block 264, the processor of thelow-power router 156 may determine whether the last communication withthe low-power router 152 occurred after some period of time has passed(e.g., 6 hours). Generally, a pair of communicating devices may allowtheir clocks to be synchronized with each other if they are able tomaintain regular communication with each other. That is, if the twodevices regularly communicate with each other, they may exchange timesynchronization information to ensure that the respective clock of eachdevice is in sync with each other.

If the last communication with the low-power router 152 occurred afterthe amount of time has passed, the processor may proceed to block 262and send a chain of wake-up packets 212. In one embodiment, the chain ofwake-up packets 212 may include three wake-up packets 212 as shown inFIG. 16. The transmission of the wake-up packets 212 may involve sendingthe wake-up packet 212 and waiting a certain amount of time to receivean acknowledgment for the reception of the wake-up packet 212. In oneembodiment, the chain of wake-up packets 212 are transmitted during thereceiver sniff interval 214. As such, the receiver sniff interval 214may include a sufficient amount of time to receive at least one wake-uppacket 212 of the chain of wake-up packets 212 even when the clock ofthe low-power router 152 shifts ahead or behind the clock of thelow-power router 156. For example, the time between the start of twoadjacent wake-up packets 212 of the chain of wake-up packets 212 may beless than the duration of the receiver sniff interval 214, therebybetter ensuring that the start of a wake-up packet 212 will be detectedduring the receiver sniff interval 214. In other words, if the start ofa first wake-up packet 212 drifts to the left (e.g., earlier), outsideof the sniff interval 214, the start of subsequent wake-up packet 212should be within the sniff interval 214 and account for the size of thefirst wake-up packet 212 and any interframe spacing.

By sending the chain of wake-up packets 212 centered at the receiversniff interval 214, the processor may increase the likelihood that thelow-power router 152 may receive the wake-up packet 212 when therespective clocks of the low-power router 156 and the low-power router156 are not in sync with each other or has drifted more than Δt_(sniff).In one embodiment, the processor may continuously send a wake-up packet212 and wait an amount of time to receive the acknowledgment packet 216until the acknowledgment packet 216 has been received. As such, theprocessor may stop sending the wake-up packets 212 after theacknowledgment packet 216 has been received.

Referring back to block 264 of FIG. 14, if the last communication fromthe low-power router 152 occurred before the amount of time passed, theprocessor may proceed to block 262. At block 262, the processor may senda single wake-up packet 212 as described above with respect to FIGS.10-12.

If the last communication from the low-power router 152 (e.g., neighbornode) did not occur before the expected amount of time passed, theprocessor may proceed to block 265. At block 265, the processor maydetermine whether data expected to be received from the low-power router152 or a check-in message from the low-power router 152 was missed. Ifthe processor expects to receive data from the low-power router 152 anddid not receive the expected data from the low-power router 152, theprocessor may proceed to block 266. If the processor expects to receivedata from the low-power router 152 and did receive the expected datafrom the low-power router 152, the processor may proceed to block 262and send a single wake-up packet 212 as described above.

At block 266, the processor may determine whether the low-power router152 is available for communication for a scheduled time slot. If thelow-power router 152 is not available during the scheduled time slot,the processor may proceed to block 262 and send the chain of wake-uppackets 212 as described above. Otherwise, if the low-power router 152is available during its scheduled time slots, the processor may proceedto block 261 and send a single wake-up packet 212.

It should be noted that blocks 264-266 provide examples in which thelikelihood of clocks of the low-power router 152 and the low-powerrouter 156 being out of sync is determined. It should be understood thatthe blocks 264-266 are merely examples and additional techniques andalgorithms may be employed to determine that the likelihood of clocks ofthe low-power router 152 and the low-power router 156 are out of sync.Moreover, although the method 263 has been illustrated in a certainorder, it should be understood that the blocks depicted in FIG. 14 maybe performed in any suitable order.

When transmitting the chain of wake-up packets 212, the processor mayuse an expected amount of drift time between the clocks of the low-powerrouter 152 and the low-power router 156 to determine a number of wake-uppackets 212 in the chain of wake-up packets 212. For example, FIG. 15illustrates a method 267 for determining a number of wake-up packets 212to transmit in the chain of wake-up packets 212 described above.

In one embodiment, at block 268, the processor may determine anapproximate amount of time drift in synchronization between the clocksof the low-power router 152 and the low-power router 156. Theapproximate amount of time drift may be determined based on an amount oftime from a last known communication, the estimated drift rate ofbetween two nodes, time information provided by another node, or thelike.

After determining the approximate amount of time drift that may bepresent between the clocks of the low-power router 152 and the low-powerrouter 156, the processor may proceed to block 269. At block 269, theprocessor may determine a number of wake-up packets 212 to transmit inthe chain of wake-up packets 212. In one embodiment, the number ofwake-up packets 212 may be directly proportional to the approximateamount of time drift that may be present between the clocks of thelow-power router 152 and the low-power router 156.

In certain embodiments, the low-power router 152 may activate itsreceiver for a shorter amount of time as compared to the receiver sniffinterval 214 described above. That is, the low-power router 152 mayactivate its receiver for a first amount of time (e.g., 0.2 ms),deactivate its receiver for a second amount of time (e.g., (1.6 ms), andactivate its receiver again for a third amount of time (e.g., 0.2 ms).In other words, the low-power router 152 may perform a double sniffduring the receiver sniff interval 214. With this in mind, FIG. 17illustrates a timing diagram 280 that illustrates how the low-powerrouter 156 may activate its receiver according to a double sniff scheme.

Referring to FIG. 17, the low-power router 156 may transmit a chain ofwake-up packets 212, such that it may be centered at the receiver sniffinterval 214 (e.g., time T₂). By sending the wake-up packet 212 centeredat time T₂ and using the double receiver sniff process described above,the low-power router 152 may detect the radio frequency energy of thewake-up packet 212 when the clocks of the low-power router 152 and thelow-power router 156 have drifted apart from each other. For example, ifthe clock of the low-power router 156 has drifted ahead of the clock ofthe low-power router 152, the low-power router 156 may send the wake-uppacket 212 too early when attempting to send the wake-up packet 212centered at time T₂. In this case, the low-power router 152 may detectthe wake-up packet 212 during its first sniff 282 of the double sniff,which may correspond to the end of the wake-up packet 212. In the samemanner, if the clock of the low-power router 156 has drifted behind ofthe clock of the low-power router 152, the low-power router 156 may sendthe wake-up packet 212 too late when attempting to send the wake-uppacket 212 centered at time T₂. However, the low-power router 152 maydetect the wake-up packet 212 during its second sniff 284 of the doublesniff, which may correspond to the beginning of the wake-up packet 212.

After detecting the transmission of the wake-up packet 212, thelow-power router 152 may keep its receiver active to receive asubsequent wake-up packet 212 transmitted from the low-power router 156.After transmitting the wake-up packet 212, the low-power router 156 maybegin preparing to receive an acknowledgment packet 216 from thelow-power router 152. The acknowledgment packet 216 may include dataindicating that the wake-up packet 212 was received properly (e.g.,without errors) by the low-power router 152. As such, after low-powerrouter 156 receives the wake-up packet 212, the low-power router 152 mayprocess the wake-up packet 212 and prepare to transmit theacknowledgment packet 216 to the low-power router 156.

With the foregoing in mind, FIG. 18 illustrates a flow chart of a method290 that a processor of a receiving device may use for employing adouble sniff scheme for receiving the wake-up packet 212. For thepurposes of discussion, the following description will be presented asbeing performed by the processor of the low-power router 152 (i.e.,receiving device).

At block 292, the processor may activate its receiver using the doublesniff technique discussed above during the sniff interval 214. Althoughthe following description of the method 290 is discussed using a doublesniff technique, it should be noted that the processor may activate itsreceiver using a triple sniff technique, quadruple sniff technique, ofany other suitable sniff variation. Regardless of the number of sniffsemployed by the processor, at block 294, the processor may determinewhether any energy (e.g., radio frequency energy) has been detectedduring the sniff interval 214.

If the processor does not detect radio frequency energy, the processormay proceed to block 296 and wait to activate its receiver again at thenext wake slot according to the communication schedule 200. If theprocessor does detect radio frequency energy during one of its sniffs,the processor may proceed to block 298. At block 298, the processor maykeep its receiver active to receive the wake-up packet 212. That is,since the wake-up packet 212 was likely the detected energy of block294, the processor may keep its receiver on to receive the nexttransmitted wake-up packet 212 in the chain of wake-up packets, asillustrated in FIG. 15.

At block 300, the processor may receive the wake-up packet while itsreceiver is on after detecting the energy at block 294. After receivingthe wake-up packet 212, at block 302, the processor may transmit theacknowledgment packet 216 to the low-power router 152 (e.g.,transmitting device).

By employing the double receiver sniff process described above, thelow-power router 152 (i.e., receiving device) may use power moreefficiently as compared to activating its receiver during the entiresniff interval 214. Additionally, by transmitting the wake-up packet 212during the fixed wake-up slot 202, the low-power router 156 (i.e.,transmitting device) does not blast or continuously transmit a wake-uppacket across one or more communication channels for an extended amountof time when attempting to send data to neighboring devices. That is,instead of blasting wake-up packets for an extended period of time, thetransmitting device may send a repeated sequence of wake-up packets, butsince there is a common time reference, it can send a much shortersequence of such wake-up packets. For example, a 20 ms blast of a chainof wake-up packets can be sent, as opposed to a 4000 ms blast.

The specific embodiments described above have been shown by way ofexample, and it should be understood that these embodiments may besusceptible to various modifications and alternative forms. It should befurther understood that the claims are not intended to be limited to theparticular forms disclosed, but rather to cover all modifications,equivalents, and alternatives falling within the spirit and scope ofthis disclosure.

What is claimed is:
 1. A system configured to communicate according to acommunication schedule comprising a plurality of frames, each frame ofthe plurality of frames being organized according to a grid of cells,each of the cells being associated with one of a plurality ofcommunication channels and one of a plurality of time slots, the systemcomprising: a first electronic device configured to activate a receiveraccording to the communication schedule to receive a wake-up packet thatindicates there are data packets to receive from a second electronicdevice by: activating the receiver relative to a time slot on acommunication channel for a first duration of time; deactivating thereceiver for a second duration of time after the first duration of timeexpires to reduce power consumption by the first electronic device; andreactivating the receiver relative to the time slot on the communicationchannel for a third duration of time after the second duration of timeexpires, the timing of the activation and the reactivation beingdisposed about the time slot on the communication channel to account forclock drift of the first electronic device, the second electronicdevice, or both; and the second electronic device configured tocommunicate with the first electronic device by: transmitting thewake-up packet during the time slot on the communication channel, thetime slot and the communication channel being associated with a cell inthe communication schedule at a known position in each frame of theplurality of frames of the communication schedule, and the firstelectronic device being configured to perform an operation based onreceiving the wake-up packet; and in response to the first electronicdevice receiving the wake-up packet, receiving, from the firstelectronic device, an acknowledgment packet associated with the wake-uppacket.
 2. The system of claim 1, wherein the second electronic deviceis configured to communicate with the first electronic device bytransmitting one or more data packets to the first electronic devicewhen the first electronic device is configured to activate the receiverbased on the communication schedule.
 3. The system of claim 1, whereinthe grid of cells indicates at least one time slot and a correspondingcommunication channel in which a pair of electronic devices arescheduled to communication with each other.
 4. The system of claim 1,wherein the first duration of time and the third duration of timecomprises approximately 2 mSec, and wherein the second duration of timecomprises approximately 1.6 mSec.
 5. The system of claim 1, wherein eachframe of the plurality of frames of the communication schedule comprisesat least one cell that is associated with a pair of devices in arespective grid.
 6. The system of claim 5, wherein the at least one cellis in a fixed position in the respective grid of each frame of theplurality of frames.
 7. The system of claim 1, wherein the firstelectronic device and the second electronic device are configured tooperate in a low-power mode by operating in a sleep mode for a firstperiod of time and awaking periodically to detect data transmissions. 8.The system of claim 1, wherein the first electronic device is configuredto: receive the wake-up packet after detecting that the wake-up packetis being transmitted during the time slot on the communication channel;synchronize a clock associated with the first electronic device based onthe wake-up packet; verify that the wake-up packet is received free ofany error; and based upon verification of the wake-up packet, send theacknowledgment packet to the second electronic device.
 9. An electronicdevice configured to communicate with a plurality of electronic devicesdisposed in a building according to a communication schedule comprisinga plurality of frames, each frame of the plurality of frames beingorganized according to a grid of cells, each of the cells beingassociated with one of a plurality of communication channels and one ofa plurality of time slots, the electronic device comprising a processorconfigured to: receive an indication of data to be transmitted toanother electronic device of the plurality of electronic devices;identify a cell in a frame of the grid of the communication schedule inwhich the electronic device and the other electronic device arescheduled to communicate with each other, the cell being associated witha time slot and a communication channel for the communication; andtransmit a plurality of wake-up packets centered at a time within thetime slot to the other electronic device, each of the plurality ofwake-up packets being configured to cause the other electronic device toperform an operation based on receiving one of the wake-up packets. 10.The electronic device of claim 9, wherein the processor is configured totransmit one or more data packets associated with the data afterreceiving an acknowledgment associated with one of the plurality ofwake-up packets.
 11. The electronic device of claim 9, wherein the datacomprises alarm information, one or more sensor measurements, one ormore commands, or any combination thereof.
 12. The electronic device ofclaim 9, wherein a number of the plurality of wake-up packets isdetermined based on an expected amount of time drift between theelectronic device and the other electronic device.
 13. The electronicdevice of claim 9, wherein the operation comprises instructionsconfigured to control one or more operations of one or more devices inthe building.
 14. The electronic device of claim 9, wherein theprocessor is configured to transmit the plurality of wake-up packetsduring the time slot, such that the transmission of the plurality ofwake-up packets is centered about a double sniff interval of the otherelectronic device.
 15. The electronic device of claim 9, wherein the oneof the plurality of wake-up packets comprises time synchronizationinformation associated with a clock of the electronic device.
 16. Theelectronic device of claim 9, wherein the processor is configured totransmit the plurality of wake-up packets when communication between theelectronic device and the other electronic device has not occurred for aperiod of time, when the processor determines that an expected datapacket from the other electronic device has not been received, when theprocessor determines that the other electronic device is not availableduring a scheduled time according to the communication schedule, or anycombination thereof.
 17. A method, comprising: receiving, via aprocessor of a communication device, a communication schedule comprisinga plurality of frames, each frame of the plurality of frames beingorganized according to a grid of cells, each of the cells beingassociated with one of a plurality of communication channels and one ofa plurality of time slots; activating, via the processor, a receiveraccording to the communication schedule and using a double sniffinterval, the receiver being configured to receive data packets fromanother communication device, and the receiver being activated duringone of the plurality of time slots and on one of the plurality ofcommunication channels, the double sniff interval being disposed aboutthe one of the plurality of time slots and on the one of the pluralityof communication channels; detecting, via the processor, energy of awake-up packet when the receiver is activated; and activating, via theprocessor, the receiver for a duration of time when the energy isdetected, the duration of time corresponding to an amount of time toreceive the wake-up packet.
 18. The method of claim 17, comprising:determining, via the processor, time information associated with theother communication device that is included in the wake-up packet; andadjusting, via the processor, a clock of the communication device basedon the time information.
 19. The method of claim 17, wherein thecommunication device comprises a thermostat, a hazard detector, or aportable electronic device, and wherein the wake-up packet comprisesinstructions to perform an operation configured to adjust a condition ina building.
 20. The method of claim 17, wherein using the double sniffinterval comprises: activating the receiver relative to the one of theplurality of time slots on the one of the plurality of communicationchannels for a first duration of time; deactivating the receiver for asecond duration of time after the first duration of time expires toreduce power consumption by the communication device; and reactivatingthe receiver relative to the time slot on the communication channel fora third duration of time after the second duration of time expires.